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Compared with the use of phase-insensitive linear quantum amplifiers of the same gain G, the use of phase-sensitive linear amplifiers on phase coherent classical light sources in an amplifier–attenuator chain reduces the total quantum noise power by a factor of 4, the homodyne noise variance by 2, and the photon number variance by 2–8 and suppresses the Kerr effect linear phase fluctuation variance as well as the soliton timing-error variance by 2G2. | For the first time, a monolithically integrated photonic phase-sensitive amplification chip is fabricated and demonstrated based on an InP/InGaAsP platform. Different semiconductor optical amplifiers have been fabricated as well for characterization. On the chip, two tunable laser pumps that are coherently injection-locked, respectively, from two first-order sidebands of an externally modulated tone are generated to enable signal-degenerate dual-pumped phase-sensitive amplification in a saturated semiconductor optical amplifier. Experiments on different chips are conducted to successfully demonstrate phase-sensitive amplification with approximately 6.3 and 7.8 dB extinction of phase-sensitive on-chip gain. Theoretical simulations are performed and agree well with experimental results. The additive noise properties of the phase-sensitive amplification chip are also investigated. | Dispersive transform spectral imagers with both one- and two-dimensional spatial coverage have been demonstrated and characterized for applications in remote sensing, target classification and process monitoring. Programmable spatial light modulators make it possible to adjust spectral, temporal and spatial resolution in real time, as well as implement detection algorithms directly in the digitally controlled sensor hardware. Operating parameters can be optimized in real time, in order to capture changing background and target evolution. Preliminary results are presented for short wave, mid-wave, and long-wave infrared sensors that demonstrate the spatial and spectral versatility and rapid adaptability of this new sensor technology. | eng_Latn | 7,700 |
Optical intensity modulators with closely matched frequency responses are required for the realization of an optical adaptive nulling system for microwave/millimeter-wave multi-element antenna systems. Traveling-wave interferometric modulators fabricated in lithium niobate have been demonstrated that track to within 0.03 dB and 0.22 deg in amplitude and phase, respectively, over the 5- to 7-GHz frequency band. | The performance of three optics-based interference cancellation systems are compared and contrasted with each other, and with traditional electronic techniques for interference cancellation. The comparison is based on a set of common performance metrics that we have developed for this purpose. It is shown that thorough evaluation of our optical approaches takes into account the traditional notions of depth of cancellation and dynamic range, along with notions of link loss and uniformity of cancellation. Our evaluation shows that our use of optical components affords performance that surpasses traditional electronic approaches, and that the optimal choice for an optical interference canceller requires taking into account the performance metrics discussed in this paper. | Manufacture and in-service assessment of composite materials can be challenging since there is, yet, no standard method for testing them. Nevertheless, regular inspection is necessary to maintain the structural integrity. This paper describes a nondestructive, broadband noise mapping method that uses a millimeter-wave radiometer to detect defects in composite materials. The $W$ -band system is configured for transmission mode measurement in which an amplified photonic source illuminates a glass fiber reinforced polymer containing machined defects. A high sensitivity radiometer is used for imaging the sample. The radiometer consists of a Schottky diode-based frequency tripler and a fundamental mixer. | eng_Latn | 7,701 |
The terahertz(THz) technique has attracted much attention from a variety of applications in fundamental and applied research field,such as physics,chemistry,life sciences,medical imaging,safety inspection,radio astronomy,modern communication,weapon guidance and so on.THz radiation source is a crucial part of THz techniques system.Some typical techniques of the generation of THz radiation based on the optical methods,especially the nonlinear optical process such as difference frequency generation(DFG) and THz parametric generation(TPG) based on stimulated polariton scattering process,are briefly introduced and reviewed.The future of these two kinds of THz generation methods is also forecast. | CO 2 -pumped THz laser was used to measure a new SiO 2 matrix ceramic composite sample's transmittance. Experimental transmission data reported here were obtained respectively at wavelengths of 118.83μm, 122.4μm, 158.51μm, 184.31μm and 214.58μm. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 7,702 |
The generation and accumulation of random jitter (RJ) in channels using multimode fibers (MMF) and vertical cavity surface emitting lasers (VCSEL) is investigated. A novel theoretical model that accommodates mode partition noise (MPN) and modal-chromatic dispersion interaction (MCDI) for the length dependence of RJ in VCSEL-MMF channels is developed. The proposed model requires a few channel parameters such as length, MPN coefficient, spectral width of the source, and a new parameter for describing the modal-chromatic interaction. Simulation predictions are verified by experiments. | Mode partition noise may become the dominant performance limitation for single-mode fiber systems. We define the mode partition coefficient k for laser diodes which can be used as a universal index, like threshold current and spectral width, to characterize laser diodes. The k value varies between 1 and 0, and for larger k , the mode partition noise will be higher. We also demonstrate two simple techniques for measuring k : the low-pass filter method and the sampling method. We discuss the k values measured under different operating conditions (pulse width, dc bias) for several types of laser diodes, k values are around 0.4-0.6 with short pulse width (1.5-5ns), and decreases to 0.14 pulse width of 50 ns. The largest k values were obtained for a laser exhibiting strong relaxation oscillation. For that laser, k did not depend on the pulse width. The k value is an important factor for system and fiber design as well as laser diode design. | Conjugacy separability of any group of the class of one-relator groups given by the presentation $ $ ($m,n>1$) is proven. | eng_Latn | 7,703 |
We firstly propose and demonstrate a new economical approach that can correct the wavefront of the petwatt Ti:sapphire laser system with a beam size of 150mm. By using a deformable mirror with 50mm active aperture in the end of the laser, the focal spot size is reduced effectively. The experimental results show that the new approach is simple, less-expensive and valid from a technical and economical point. This technique could be applied to correct the wavefront of a large optical beam with a smaller aperture deformable mirror. | Unimorph DMs are attractive for laser beam shaping due to their advantages of simplicity, compact, low cost and large ::: stroke. This paper reports a novel unimorph deformable mirror used for laser beam shaping. The developed DM consists of ::: both an inner actuator array and an outer ring actuator. The inner actuator array is used for aberration correction, while the ::: outer ring actuator is used to generate an overall defocus bias. A laser beam shaping experimental setup with a He-Ne laser ::: was constructed. The correction capability of the DM is demonstrated by simulation and experiment. | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 7,704 |
We report the characteristics of an erbium-doped GaN semiconductor waveguide amplifier grown by metal-organic chemical vapor deposition. We demonstrated that both 980 and 1480 nm optical pumping were efficient to create population inversion between the I413/2 and I415/2 energy levels. The carrier lifetime in the I413/2 energy band was measured to be approximately 1.5 ms in room temperature, which is slightly shorter than that in erbium-doped silica due to the interaction between the erbium ions and the semiconductor lattice structure. But it is significantly longer than the carrier lifetime in a typical semiconductor optical amplifier which is in the nanosecond regime. | Excitation cross section of erbium-doped GaN waveguides is measured to be approximately 2.2×10−21cm2 at 980 nm pumping wavelength. This cross section value is found relatively insensitive to the crystalline quality of epilayers. However, spontaneous emission carrier lifetimes in these waveguides are directly related to both the crystalline quality and the optical loss, and thus can be used as a material quality indicator. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 7,705 |
In this paper, we investigate the presence of time delay (TD) signature in chaotic intensity outputs of nanolasers subject to different optical feedbacks (OFs). Simulation results reveal the occurrence of obvious TD feature for the cases where conventional, phase conjugate and grating mirror feedbacks are employed. So, a proposed scheme for generating optical chaos with concealed TD signature is proposed to overcome the drawbacks of previously mentioned OFs and render the system more appropriate for applications of secure communications and fast physical random number generators. | In this paper, we present a polarization-assisted $L$ -ary differential phase-shift keying multipulse pulse-position modulation (PA. $L$ DPSK-MPPM) technique that is secured in the physical layer by a discrete-chaos system. The all-optical PA. $L$ DPSK-MPPM scheme benefits from the polarization as an additional degree of freedom which greatly reduces the system complexity relative to prior implementations. The discrete-chaos scrambling is based on a message-seeded two-dimensional chaotic map tailored for independent perturbation of the occupied time-slot positions (MPPM information) and their relative phase shift ( $L$ DPSK information). Synchronized and non-synchronized implementations of the chaotic PA. $L$ DPSK-MPPM technique are proposed with expressions for the corresponding spectral efficiencies being determined and compared with prior $L$ DPSK-MPPM setups. The performance of PA. $L$ DPSK-MPPM under gamma-gamma (GG) free-space optical (FSO) fading channels is analytically verified to outperform the prior designs for different FSO channel states which is supplemented by Monte Carlo (MC) simulations. The system security is numerically examined against various types of attacks, including brute-force, differential, and statistical attacks. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 7,706 |
We investigate a simple and flexible scheme of all fiber Fabry-Perot filter with continuous free spectral range tunability and its application to a multiwavelength SOA laser with eleven lasing channels at room temperature. | We design superimposed in-fiber grating structures to work as multi-channel real-time optical spectrum analyzers for wavelength-division-multiplexing applications. The potential applications of the technique proposed here, as well as extensions to other signal treatments, are also analyzed. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 7,707 |
We propose a novel optical-beam-induced current (OBIC) measurement technique to detect the degradation of the interior of a laser waveguide. OBIC topographies were obtained with incident transverse-magnetic-mode light, such that OBIC became sensitive to interior degradation. We additionally used transverse-magnetic-mode and transverse-electric-mode lights to confirm that the degradation region of $t^{0.5}$ deterioration is mainly located in the active layer, not in the vicinity of the antireflection facet. | We investigated the degradation behavior of distributed feedback lasers by employing the optical-beam-induced current measurement technique. We showed that the degradation mechanism is governed by diffused defects at the waveguide other than those in the vicinity of the antireflection facet. In addition, we found that a diffused source is probably generated in the upper InP cladding layer above the grating during the growth of the upper InP cladding layer. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 7,708 |
We search for efficient schemes of second and terahertz harmonic generation in nanocomposites consisted of metal-oxide semiconductor quantum dots incorporated into a dielectric matrix, when the quantum dots are in resonance and the dielectric matrix is out of resonance with femtosecond light pulse. It’s established that large efficiency of frequency up-conversion is possible to attain, which may be for the optimal quantum dot concentration in above mentioned nanocomposites by 70% higher than in pure nonlinear dielectric matrix. | Recently we observed ultrafast laser-induced phase transition (on a time scale less than 100 fs) to a centrosymmetric semiconductor-like phase at the GaAs surface [1,2] by using time-resolved second harmonic generation in reflection. A phenomenological model describing this phase transition is developed. The new phase exists during the first 1 ps after laser excitation due to high plasma carrier density and lattice stress, the lattice temperature remaining well below the melting threshold. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 7,709 |
We have observed Ar2* emission at 126 nm by use of a high intensity laser pulse as an excitation source. Kinetic analysis revealed that high-intensity laser-produced electrons via optical field induced ionization (OFI) process initiated the Ar2* production kinetics. Ar2* production kinetics initiated by OFI electrons was mainly governed by the three-body association process, which was analogous to the case of electron beam excitation. The use of a hollow fiber controlled propagation characteristics of a high intensity laser pulse in a high-pressure gas, leading to the increase of the excimer emission intensity© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | Successful oscillation of a tunable, high-power argon excimer laser is reported. The wavelength was tuned from 124.5 to 127.5 nm with a spectral width of 0.3 nm. The output power of 2.2 MW, obtained at the line center, is 3 orders of magnitude larger than the value reported previously by Wrobel et al. [Appl. Phys. Lett. 36, 113 (1980)]. The possibility of frequency conversion of the argon excimer laser radiation to other wavelengths by a stimulated Raman scattering process is discussed. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 7,710 |
A two-dimensional, electromagnetic, electron fluid computer code predicts picosecond-scale electromagnetic wave generation in a simple air avalanche switch. Similar pulses occur from kilovolts to megavolts for proper scaling of the pressure. At fixed voltage, the pulse width varies with pressure. At fixed pressure, the pulse width varies with voltage. The pulse width can be reduced to 1-2 ps by operation in the wave interference mode. In this mode, one air gap fires with a slight delay from the other air gap. This delay is some fraction of a picosecond. | The gas avalanche switch is a laser-activated, high-voltage switch, consisting of a set of pulse-charged electrodes in a high-pressure gas.1–4 Induced electrons from a picosecond-scale laser pulse initiate an avalanche discharge between high-voltage and grounded electrodes. If the voltage, pressure, and dimensions are correct, the rapid avalanche, fueled by the immense number of electrons available in the gas, collapses the applied voltage in picoseconds and generates electromagnetic pulses with widths as short as 1–10 ps and 3 dB bandwidths of 20–120 GHz. With proper voltage or pressure detuning, wider pulses and lower bandwidths occur. In addition to picosecond electromagnetic pulse generation, application of this switch should result in ultra-fast Marx bank pulsers.5 | not available DOI: http://dx.doi.org/10.3329/pulse.v5i2.20263 Pulse Vol.5 July 2011 p.31-40 | eng_Latn | 7,711 |
We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally investigate the influence of the dispersion profile, and we show that a hybrid configuration combining dispersion decrease and gain has several benefits on the parabolic generated pulses. | Parabolic pulses in optical fibers have stimulated an increasing number of applications. We review here the physics underlying the generation of such pulses as well as the results obtained in a wide-range of experimental configurations. | not available DOI: http://dx.doi.org/10.3329/pulse.v5i2.20263 Pulse Vol.5 July 2011 p.31-40 | eng_Latn | 7,712 |
A novel optical single-sideband (OSSB) signal generation with simultaneous IF signal up conversion technique is proposed to overcome the fiber dispersion problem. With this up-conversion technique, a high frequency OSSB signal is generated by using two low bandwidth intensity modulators in combination with fiber gratings. The low frequency local oscillator (LO) signal is modulated by employing frequency doubling technique or frequency quadrupling technique respectively. The OSSB radio frequency (RF) signal generated by mixing the intermediate frequency (IF) signal and low frequency local oscillator (LO) signal, is transmitted over standard single-mode fiber successfully. The received signal error vector magnitude (EVM) is 5.8% rms and 13% rms. | An all-optical frequency upconversion technique using a quasi optical single sideband (q-OSSB) signal in a nonlinear semiconductor optical amplifier (NSOA) for radio-over-fiber applications is proposed and experimentally demonstrated. An optical radio frequency signal (f(RF) = 37.5 GHz) in the form of a q-OSSB signal is generated by mixing an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) with an optical local oscillator signal (f(LO) = 35 GHz) utilizing coherent population oscillation and cross gain modulation effects in an NSOA. The phase noise, conversion efficiency, spurious free dynamic range (SFDR), and transmission characteristics of the q-OSSB signal are investigated. | An all-optical frequency upconversion technique using a quasi optical single sideband (q-OSSB) signal in a nonlinear semiconductor optical amplifier (NSOA) for radio-over-fiber applications is proposed and experimentally demonstrated. An optical radio frequency signal (f(RF) = 37.5 GHz) in the form of a q-OSSB signal is generated by mixing an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) with an optical local oscillator signal (f(LO) = 35 GHz) utilizing coherent population oscillation and cross gain modulation effects in an NSOA. The phase noise, conversion efficiency, spurious free dynamic range (SFDR), and transmission characteristics of the q-OSSB signal are investigated. | eng_Latn | 7,713 |
We developed 8 times 8 beam-deflecting optical switch with a switching speed within one microsecond utilizing electro-optic effect of PLZT. A newly-developed radial optical path design and putting-in packaging structure with a monolithic PLC platform were applied. | We investigate the feasibility of implementing an elementary building block for quantum information processing. The combination of a deterministic single photon source based on vacuum stimulated adiabatic rapid passage, and a quantum memory based on electromagnetically induced transparency in atomic vapour is outlined. Both systems are able to produce and process temporally shaped wavepackets which provides a way to maintain the indistinguishability of retrieved and original photons. We also propose an efficient and robust `repeat-until-success' quantum computation scheme based on this hybrid architecture. | Background ::: The optimal treatment for elderly patients with early-stage non-small cell lung cancer (NSCLC) remains inconclusive. Previous studies have shown that stereotactic body radiotherapy (SBRT) provides encouraging local control though higher incidence of toxicity in elderly than younger populations. The objective of this study was to compare the outcomes of SBRT and surgical treatment in elderly patients with clinical stage I-II NSCLC. | eng_Latn | 7,714 |
This paper describes the effects of barrier-state carriers on the modal gain of InGaAs-GaAs quantum-well (QW) lasers emitting at 980 nm. Experimental studies and numerical simulations are used to examine several drive configurations, each having a unique effect on the laser response. These include compound drive current shapes, optical excitations and fast electrical drives with rise times shorter than 100 ps. We demonstrate that a large barrier-state carrier density affects the index of refraction sufficiently so as to cause a reduction in the confinement factor and modal gain which is large enough to turn the laser off. | We perform a theoretical study of carrier transport effects in the frequency modulation response of single-mode quantum well (QW) lasers under both small and large signal modulations. The lasers considered are ultra-high speed InGaAs/GaAs MQW lasers with intrinsic modulation bandwidth of 40 GHz. A rate-equation model, including spontaneous emission noise, for the carriers in the active region (quantum wells) N w , the carriers in the separate confinement heterostructure and in the barriers (core) N c and for the optical field is used. Carrier transport effects are included by considering two effective time constants: the transport/capture time, and the re-emission time out of the QW's (escape time). We also consider the change in the laser frequency due to the refractive index changes in both the wells and the core. In the wells the laser frequency increase with N w is described by the linewidth enhancement factor. Since the laser frequency is below the bandgap in the core, the refractive index change with N c , dn c /dN c , can be positive or negative depending on the doping level. When dn c /dN c > 0 the magnitude of the FM response decreases when the capture (escape) time increases (decreases), but the shape is flat. We have also studied the frequency statistics under large signal modulation. A linear relationship between frequency chirp range and turn-on time is obtained, as in bulk lasers. For QW lasers biased below threshold the chirp range is found to increase (decrease) for large capture times when dn c /DN c is positive (negative) due to the contribution of the carriers in the core. The opposite behavior is found for small escape times. | We report nearly complete preservation of “spin memory” between optical absorption and photoluminescence under excitation >0.2 eV above the band gap in nanometer GaSe slabs. | eng_Latn | 7,715 |
A piezo-tuned CW, single-mode, narrow-linewidth distributed feedback, photonic crystal fibre (DFB-PCF) laser was fabricated. To determine its stability, the laser was used to measure the linewidth of the P11 molecular absorption band of acetylene (C2H2) with a resolution of 0.45pm and a tuning range of 0.22nm. | We demonstrate a stable, CW, single-mode distributed feedback (DFB) photonic crystal fibre (PCF) ring laser with a narrow linewidth of <10 kHz. The incorporation of a polarisation-discriminating feedback loop helps eliminate the detrimental effect of self-pulsing and allows lasing to occur in one single longitudinal mode. | We demonstrate a stable, CW, single-mode distributed feedback (DFB) photonic crystal fibre (PCF) ring laser with a narrow linewidth of <10 kHz. The incorporation of a polarisation-discriminating feedback loop helps eliminate the detrimental effect of self-pulsing and allows lasing to occur in one single longitudinal mode. | eng_Latn | 7,716 |
Coherent beam combination of two thulium-doped fiber laser beams using a multi-dithering technique is presented for the first time. In the experiment, two fiber lasers centered at 1948.6 nm are coherently combined, and a phase modulator based on piezoelectric ceramics transducer is connected in one beam path to compensate for the phase errors between the two beams. When the phase control system is closed loop, the fringe contrast of the far-field intensity pattern is improved to be more than 75%, from 15% in open-loop, and the residual phase error is less than λ /20. The experimental results show that the performance of the phase control system is robust and the control bandwidth is more than 1 kHz, which indicates that the above approach can be scaled to facilitate the coherent beam combination of kilo-watt level thulium-doped fiberlaser. | We present a high-power single frequency (SF) Tm-doped fiber amplifier employing all-fiber master oscillator power amplifier (MOPA) configuration. An SF fiber laser with ultrashort cavity and output power of $\sim 40$ mW was used as the seed laser of the MOPA, and the central wavelength located at $\sim 1971$ nm. The final output power of the MOPA reaches 310 W with slope efficiency of 0.56, and no amplified spontaneous emission or parasitic lasing is observed. The stimulated Brillouin scattering threshold is not reached yet, and the output power is only pump limited. This is the first demonstration, to the best of our knowledge, on an SF Tm-doped all-fiber MOPA with output power exceeding 300 W. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 7,717 |
A novel method to determine the linewidth of a semiconductor laser is described. By measuring the noise voltage at the electrical terminal, the electron density variations in the gain medium can be determined. Since these variations are the major cause of the linewidth of semiconductor lasers, both the linewidth and the lineshape can be determined from electrical measurements if the ?-parameter is known and the parasitic impedances of the laser are small. | The influence of parasitic elements on the wideband electrical noise in semiconductor lasers is investigated theoretically and experimentally. The results show that the maximum small-signal modulation bandwidth can be determined from measurements of the electrical noise spectrum. A small difference of the peak frequency in the optical intensity noise and the peak frequency in the electrical noise spectra is observed (about 200 MHz), and is explained by introducing the nonlinear intrinsic diode impedance in the parasitic model. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 7,718 |
We demonstrate polarized blue single photon emission up to 200 K from an In0.2Ga0.8N quantum dot in a single Al0.1Ga0.9N nanowire. The InGaN/AlGaN dot-in-nanowire heterostructure was grown on (111) silicon by plasma assisted molecular beam epitaxy. Nanowires dispersed on a silicon substrate show sharp exciton and biexciton transitions in the micro-photoluminescence spectra. Second-order correlation measurements performed under pulsed excitation at the biexciton wavelength confirm single photon emission, with a g(2)(0) of 0.43 at 200 K. The emitted photons have a short radiative lifetime of 0.7 ns and are linearly polarized along the c-axis of the nanowire with a degree of polarization of 78%. | We report and discuss the origins of linearly polarized single photon emission from site-controlled GaN nanowire quantum dots. The observed single photon emission reveals almost complete linear polarization, in agreement with studies in the literature, which could be of use for applications such as quantum key distribution. | We report and discuss the origins of linearly polarized single photon emission from site-controlled GaN nanowire quantum dots. The observed single photon emission reveals almost complete linear polarization, in agreement with studies in the literature, which could be of use for applications such as quantum key distribution. | eng_Latn | 7,719 |
The motivation of this work is the development of a laser sensor and gyroscope based on short pulse solid state ring laser. In comparison with regular ring laser containing the gain medium and saturable absorber where counterpropagating pulses overlap, a ring synchronously pumped optical parametric oscillator (OPO) where the pulse crossing point is controlled externally by the arrival time of the pump pulses is the ideal source for short pulse laser sensor. The optimum configuration is OPO synchronously pumped inside the resonator of mode-locked solid state laser. The operation of a picosecond synchronously intracavity pumped optical parametric oscillator (OPO) is reported. A magnesium doped lithium niobate crystal (MgO:PPLN), periodically poled, is used as the optical parametric oscillator crystal coupling the pump and the resonant signal cavities. The active medium of the passively mode-locked pump cavity is a diode pumped Nd:YVO 4 crystal. Continuous mode-locked operation was achieved, tunable from 1531 to 1554 nm by adjusting the OPO crystal temperature from 31 to 56 °C. The spectral width of the generated radiation was 2 nm. | Frequency coupling between the counter-propagating pulses inside a femtosecond ring laser gyroscope is studied. It is shown that frequency lock-in results from the counter-propagating pulses overlapping at or near a scattering surface. Nonetheless, the absence of lock-in with a scatterer at the pulse crossing point is demonstrated for the special case of symmetric scattering. The decoupling of the counter-propagating pulses makes possible the measurement of non-reciprocal phase differences of 10−5 and index differences of 10−10 over 1 cm. Besides measuring rotations, applications are found in the measurement of small changes in the index of refraction, and electrical transients on the 100 fs time scale. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 7,720 |
The paper deals with some investigations aimed at applying compensation techniques to reduce nonlinear signal distortion in the Mach-Zehnder modulator of HFC CATV systems. The frequency distribution of secondand third-order intermodulation products of N-channel transmission systems is shown. Models of dual-parallel and dual-cascade Mach-Zehnder modulators are suggested based on both the mathematical model of a conventional Mach-Zehnder modulator and the features of the CATV system itself, thus making it possible for the modulator parameters to be determined in a way to ensure CSO products cancellation and CTB products minimization. The dependence of the C/CTB parameter on the modulation index is studied for N-channel HFC CATV systems applying a dual-parallel or dual-cascade Mach-Zehnder modulator. Optical channels implementing dual-parallel or dual-cascade Mach-Zehnder modulator instead of a conventional one are compared and the possibilities to improve the RF signals’ dynamic range are analyzed. Relations to determine the increase of the optical loss introduced by dual Mach-Zehnder modulators are suggested that help compare it with that caused by a conventional Mach-Zehnder modulator. | We have characterized the intermodulation distortion and compression properties of an integrated optical modulator at microwave frequencies by measuring the third-order intercept and 1-dB compression points. Values of +30.0 and +21.4 dBm, respectively, were measured and agree well with theory. When operated in the shot-noise-limited regime, these devices can have spurious free dynamic ranges in excess of 100 dB, making them attractive as potential alternatives to conventional diode mixers in special applications. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 7,721 |
We have measured the relative timing jitter of two passively mode-locked 10-GHz Er:Yb:glass lasers to be 190 fs (100 Hz-1.56 MHz) in free-running and 26 fs (6 Hz-1.56 MHz) in synchronized operation. | We demonstrate a fundamentally mode-locked fiber laser with a repetition frequency in excess of 2 GHz at a central wavelength of 1.535 mum. Co-doped ytterbium-erbium fiber provides the gain medium for the laser, affording high gain per unit length, while a semiconductor saturable absorber mirror (SAM) provides the pulse shaping mechanism in a standing wave cavity. Results are shown confirming cw mode-locking for 1 GHz and 2 GHz repetition frequency systems. The response of the frequency comb output to pump power variations is shown to follow a single pole response. The timing jitter of a 540MHz repetition-rate laser has been suppressed to below 100 fs through phase-lead compensated feedback to the pump power. Alternatively, a single comb line of a 850MHz repetition-rate laser has been phase-locked to a narrow linewidth cw laser with an in-loop phase jitter of 0.06 rad(2). The laser design is compatible with low-noise oscillator applications. | We demonstrate a fundamentally mode-locked fiber laser with a repetition frequency in excess of 2 GHz at a central wavelength of 1.535 mum. Co-doped ytterbium-erbium fiber provides the gain medium for the laser, affording high gain per unit length, while a semiconductor saturable absorber mirror (SAM) provides the pulse shaping mechanism in a standing wave cavity. Results are shown confirming cw mode-locking for 1 GHz and 2 GHz repetition frequency systems. The response of the frequency comb output to pump power variations is shown to follow a single pole response. The timing jitter of a 540MHz repetition-rate laser has been suppressed to below 100 fs through phase-lead compensated feedback to the pump power. Alternatively, a single comb line of a 850MHz repetition-rate laser has been phase-locked to a narrow linewidth cw laser with an in-loop phase jitter of 0.06 rad(2). The laser design is compatible with low-noise oscillator applications. | eng_Latn | 7,722 |
A high quality Multiple Diode Laser (MDL) has been built that combines 16 Spectra Diode Lab's laser diodes into a single beam using both wavelength and polarization combining. The MDL was designed and built to space flight requirements. Critical submicrometer tolerances to achieve wavelength stability, beam collimation, and beam coalignment and stability were met using developed repeatable processes. The most stressing optomechanical requirement was the placement and cementing of an external etalon very accurately positioned 36.3 +/- 0.05 micron from the diode to control the wavelength of the diode output. The second most stressing optomechanical requirement was maintaining the source decenter from the optical axis of the collimating lens to +/- 0.09 micron to insure coalignment of the 16 diode beams. The design and process techniques used to achieve these most critical optomechauical tolerances will be described as well as MDL performance achieved through environmental testing. | Wideband Lasercour Transmitter PerformanceRobert J. SmithDepartment of Electro- Optics, McDonnell Douglas Astronautics Co.Bldg. IOTA, Area 231, P.O. Box 516, St. Louis, Missouri 63166A Wideband Lasercom Transmitter based on dichroic combination of directly modulatedGaAlAs laser beams was built, and its performance with regard to various requirements wasevaluated; these include rise and fall times, extinction ratio, modulation bandwidth, wave-length stability, power, polarization, and transverse mode structure.IntroductionSuccessful dichroic combination of beams from several independent lasers for the purposeof increased radiance depends heavily on the spectral characteristics of the individual | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 7,723 |
High frequency stabilization of a 2.2-W injection-locked laser-diode-pumped Nd:YAG laser to a high-finesse optical cavity has been realized by frequency control of the master laser. With the help of an external electro-optical modulator, the feedback bandwidth was extended to 1 MHz and the frequency noise relative to the reference cavity was suppressed to 3 x 10(-4) Hz/Hz(1/2) below 1 kHz. This feedback laser system is an ideal laser source for gravitational wave detectors, which require both ultralow frequency noise and high output power. | The highly sensitive, phase- and frequency-resolved detection of microwave electric fields is of central importance for diverse fields ranging from astronomy, remote sensing, communication and microwave quantum technology. However, present quantum sensing of microwave electric fields primarily relies on atom-based electrometers only enabling amplitude measurement. Moreover, the best sensitivity of atom-based electrometers is limited by photon shot noise to few $\mu$Vcm$^{-1}$Hz$^{-1/2}$: While going beyond is in principle possible by using squeezed light or Schrodinger-cat state, the former is very challenging for atomic experiments while the latter is feasible in all but very small atomic systems. Here we report a novel microwave electric field quantum sensor termed as quantum superhet, which, for the first time, enables experimental measurement of phase and frequency, and makes a sensitivity few tens of nVcm$^{-1}$Hz$^{-1/2}$ readily accessible for current experiments. This sensor is based on microwave-dressed Rydberg atoms and tailored optical spectrum, with very favorable scalings on sensitivity gains. We can experimentally achieve a sensitivity of $55$ nVcm$^{-1}$Hz$^{-1/2}$, with the minimum detectable field being three orders of magnitude smaller than existing quantum electrometers. We also measure phase and frequency, being able to reach a frequency accuracy of few tens of $\mu$Hz for microwave field of just few tens of nVcm$^{-1}$. Our technique can be also applied to sense electric fields at terahertz or radio frequency. This work is a first step towards realizing the long sought-after electromagnetic-wave quantum sensors with quantum projection noise limited sensitivity, promising broad applications such as in radio telescope, terahertz communication and quantum control. | We demonstrate a stable, CW, single-mode distributed feedback (DFB) photonic crystal fibre (PCF) ring laser with a narrow linewidth of <10 kHz. The incorporation of a polarisation-discriminating feedback loop helps eliminate the detrimental effect of self-pulsing and allows lasing to occur in one single longitudinal mode. | eng_Latn | 7,724 |
An all-optical triode based on a tandem wavelength converter was realized using cross-gain modulation in two reflective InGaAsP/InP semiconductor optical amplifiers. The reflective semiconductor optical amplifiers were utilized to improve output extinction ratio as well as logic operation output performance. The output signal power and extinction ratio from the first stage wavelength conversion were critical to the achievement of all-optical logic AND operation. The optical output power at the 1555 nm wavelength could be varied from 0.1 to 3.3 mW by a control beam which had the same wavelength. The output-input gain parameter can be changed from 0 to 1.6 when the average control power is altered from 0 to 48 µW. An optical memory with store/forward functions was demonstrated using the optical triode and a feedback system of the fiber. | Semiconductor optical amplifier (SOA) module, RSOA, SOA with mirror has become an essential component to be at ::: the head of negative feedback amplification effect, optimum gain, and cross-gain modulation with demand for longer ::: transmission lengths. The SOA module is expected to have an advantage of exhibiting much faster negative feedback ::: (NF) response because distance of optical signal passing through component to component is shorten than system ::: connected with fibers. Scattered degree and baseline line difference of eye-pattern diagrams demonstrated that NF effect ::: can be compensated compactness and stability from band pass filter in SOA module. Modulation degree (MD) of input ::: and output signals confirmed that SOA module with NF effect can be stabilized gain and waveguide of output signal and ::: reduced a wave distortion as well as consistent with results in eye-pattern waveform and bit error rate (BER). All-optical ::: switching triode with SOA module was realized in about 60 % output modulation degree at control power range of 0.01 ::: to 1 mW. We propose that our manufactured SOA module become strong component candidate to realize all optical ::: switching triode with NF effect for high speed optical processing in next generation. | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 7,725 |
Combinatorial pulse position modulation for power-efficient free-space laser communications | A new modulation technique called combinatorial pulse position modulation (CPPM) is presented as a power-efficient alternating to quaternary pulse position modulation (QPPM) for direct-detection, free-space laser communications. The special case of 16C4PPM is compared to QPPM in terms of data throughput and bit error rate (BER) performance for similar laser power and pulse duty cycle requirements. The increased throughput from CPPM enables the use of forward error corrective (FEC) encoding for a net decrease in the amount of laser power required for a given data throughput compared to uncoded QPPM. A specific, practical case of coded CPPM is shown to reduce the amount of power required to transmit and receive a given data sequence by at least 4.7 dB. Novel hardware techniques for maximum likelihood detection and symbol timing recovery are presented. | The present invention, a) a pyrimidylaminobenzamide compound, and b) pharmaceutical combination comprising a mTOR kinase inhibitor, and to provide a method of treating or preventing proliferative diseases using such combinations. | eng_Latn | 7,726 |
High stable power control of a laser diode | In this paper, the low and the high frequency noises of a laser diode have been analyzed. Based on the analysis a novel scheme that adapts analog and digital hybrid techniques is proposed to stabilize the output power of a laser diode. With the hybrid controller, the low and the high frequency noises of a laser diode are conspicuously reduced. By accurate calculation, the short-term stability of the output power of laser diode reaches ±0.55‰, and the long-term stability is ±0.7‰. | -We describe a simple method to generate wavelength-tunable pulses by using a semiconductor optical amplifier (SOA) as an intensity modulator and a gain medium. Wavelength tunable pulses at a repetition rate of 4.8 GHz have been generated. | eng_Latn | 7,727 |
Temporal structure of a short powerful laser pulse under an operation of ionization processes | It is shown, that the essential laser pulse energy depletion due to ionization losses occurs at rather large distances only. The process of depletion is accompanied by a significant steepening of the temporal pulse form corresponding to the formation of a sharp ionization front of a medium density. The latter, in turn, becomes sharper, suffering an inverse influence of the steeping of a laser pulse temporal structure. The analysis of spatial and temporal evolution of magnitude of the laser pulse from steepening is carried out.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | This paper presents design and characteristics of a compact, highly integrated Ka-band T/R module built by using a miniature magnetron in the transmitter chain. By implementing a solid-state modulator and microstrip design in the microwave part of the receiver, the overall size of the module has been reduced significantly. The module provides capabilities to realize Doppler date processing by using a digital coherent-on-receiver technique. | eng_Latn | 7,728 |
Tunable external cavity diode laser | (57) Abstract: In the external cavity laser device, a semiconductor diode laser, temperature control means for controlling the temperature of the laser, a current control means for controlling the injection current of the laser, and an external cavity a, the external cavity has a placement wavelength selection means to provide feedback of the laser, the temperature control means, said current control means and said wavelength selection means, the tuning range of the laser it is used to obtain an arbitrary frequency of operation of the laser device. | A simple, isothermal and autocatalytic system for the amplified detection of DNA was ingeniously designed based on target-triggered Y-shaped junction probe assembly, followed with a nicking endonuclease-mediated cascade recycling process. A superior detection limit of 0.1 pM towards the target DNA with an excellent selectivity could be achieved. | kor_Hang | 7,729 |
Optical Design of Holographic Plane Grating Double Monochromator with the Double Decked Ebert-Fastie Structure | For the need of high-precision spectral radiance measurement, a holographic plane grating double monochromator with the double decked Ebert-Fastie structure is designed. This system consists of two spherical collimating mirrors, a plane mirror, a roof mirror, two holographic plane gratings, entrance slit, exit slit and mid slit. Wavelength region from 160nm to 400nm can be scanned. This double decked design has a compact structure, high spectral resolution and low stray level. Its spectral resolution is less than 0.15nm, and stray level is 10-6, which satisfies the need of high-precision spectral radiance measurement in ultraviolet wavelength region in space. | Abstract According to the method described in reference [1], we have designed a series of corrector systems for Cassegrain telescopes automatically with an electronic computer. The calculations were carried out under the following two conditions: the primary and secondary mirrors have strictly conical surfaces, and the telescope is strictly free from third-order spherical aberration when the corrector systems are taken off. Results in this papercan be converted proportionally to real telescopes of any aperture, while the aberrations expressed in seconds of arc remain unchanged. | eng_Latn | 7,730 |
Time Simulations on Anti-Jamming Capability of Mono-Pulse Radar Seeker | To research the performance of mono-pulse active radar seeker under self-screening jamming(SSJ) and non-SSJ,the time domain models of mono-pulse angle tracking system which traced pressed noise jamming source under SSJ and nonSSJ were put forward in this paper.The simulation results showed that the performance of the angle tracking loop was quite good under SSJ,and the tracking related to the angle rate of sight for target;a large antenna directional bias would be introduced by support jamming at the antenna which intensity was bigger than target echo signal under non-SSJ.The models in this paper would be used in the anti-jamming performance research for radar seeker. | We present a study of resonant Raman scattering of trans-(CH${)}_{\mathrm{x}}$ chains embedded in polyvinylalcohol in the two different systems of polyvinylene and polarizer K. These systems show marked differences as well as common properties and are analyzed and compared with polyacetylene within the frame of the amplitude-mode model. The combined analysis of the different systems of polyacetylene having an identical phonon propagator but different types of inhomogeneity makes it a powerful tool for broader understanding of conjugated polymers and demonstrates once more the strength of the amplitude-mode model. We show that on top of the resonant Raman scattering (RRS) of polarizer K, a fine structure is resolved, which originates from vibronic transitions. Both the appearance of this vibronic structure in the RRS and its absence from the absorption spectrum are fully accounted for. The spectral sensitivity of RRS to temperature and laser intensity is shown to be the result of the increase in damping. | eng_Latn | 7,731 |
Limited Discrepancy Beam Search | Beam search reduces the memory consumption of best-first search at the cost of finding longer paths but its memory consumption can still exceed the given memory capacity quickly. We therefore develop BULB (Beam search Using Limited discrepancy Backtracking), a complete memory-bounded search method that is able to solve more problem instances of large search problems than beam search and does so with a reasonable runtime. At the same time, BULB tends to find shorter paths than beam search because it is able to use larger beam widths without running out of memory. We demonstrate these properties of BULB experimentally for three standard benchmark domains. | We present preliminary findings regarding an optical cross-bar switch concept based on integrated silicon photonics waveguides and a MEMS device. Finite difference time domain simulations were performed were performed at a wavelength of 1550 nm to validate the initial design. Simulations indicate that there is a 9 dB difference in output optical power that can be achieved between the two waveguides. | eng_Latn | 7,732 |
Optical lattices for electrons in semiconductors | We theoretically investigate the trapping of electrons in a semiconductor using counter-propagating laser beams. The presence of trion resonances leads to efficient electron trapping. Comparison to atoms and feasibility of the scheme are discussed. | PROBLEM TO BE SOLVED: To notify a user at the timing when mechanical engagement of an ink tank is assured so that the user does not stop operation of installation of the ink tank before the installation is completed.SOLUTION: In a substrate 100 are provided a light emitting portion 101 and a control unit 103 that controls the light emitting portion 101 according to a conduction state between an electrode 153a and an opposing electrode 102. A liquid tank 1 is moved by force P and a second engagement portion 6 is locked to a second engagement portion 156, so that the liquid tank 1 is mounted at a position where the mounting is completed, on a holder 150. After the liquid tank 1 passes through the position where the mounting is completed and the second engagement portion 6 is in a partial engagement with the second locking portion 156, a space between the electrode 153a and the opposing electrode 102 is changed from a non-conduction state into a conduction state.SELECTED DRAWING: Figure 6 | eng_Latn | 7,733 |
Femtosecond laser radiation frequency converters for lidar monitoring of the atmosphere | The possibility of using biaxial nonlinear crystals in the optical converters of femtosecond radiation pulses for laser sounding of the atmosphere has been studied. A method of broadband monitoring of the atmosphere composition using the differential optical absorption spectroscopy technique is described. The results of the numerical simulation of the lidar monitoring of gaseous components of the atmosphere using frequency-converted femtosecond laser radiation pulses are presented. | The paper presents results of finite-element modeling and the analysis of temperature fields on the RT-70 radio telescope main reflector arising from the influence of solar heat. The worldwide experience of the design and creation of unique constructions is analyzed and the mechanical problems of the full-circle radio telescope RT-70 are classified. The finite-element thermal analysis of the RT-70 is chosen as the primary problem to solve. Mathematical and 3D finite-element models are developed to analyze the temperature fields in the RT-70 main reflector. These models allow estimating, with high validity, temperature values in various points of the main reflector in different climate conditions and different times of day. | eng_Latn | 7,734 |
Two-Color Radiation Generated in a Seeded Free-Electron Laser with Two Electron Beams | We present the experimental evidence of the generation of coherent and statistically stable two-color ::: free-electron laser radiation obtained by seeding an electron beam double peaked in energy with a laser ::: pulse single spiked in frequency. The radiation presents two neat spectral lines, with time delay, frequency ::: separation, and relative intensity that can be accurately controlled. The analysis of the emitted radiation ::: shows a temporal coherence and a shot-to-shot regularity in frequency significantly enhanced with respect ::: to the self-amplified spontaneous emission | Abstract In this paper we present a new correction method of inner filter effects that occurs when measuring fluorescence Excitation–Emission Matrices (EEM) of concentrated solutions. While traditional method requires absorption measurement or sample dilution(s), the Mirrored Cell Approach (MCA) only requires two different EEM of the considered sample: a first one using a traditional cell and a second one using a mirrored cell. The mathematical relationship between both models is originally exploited to obtain a simple numerical correction. Method is validated using a set of known mixtures. In addition we show that advanced multilinear analysis can be efficiently applied on to the corrected EEM. | eng_Latn | 7,735 |
Improved tomographic imaging of wavelength scanning digital holographic microscopy by use of digital spectral shaping. | The technique of wavelength scanning digital holographic microscopy (WSDHM) is improved by use of a digital spectral shaping method which is used to suppress the sidelobes of the amplitude modulation function in WSDHM for non-Gaussian-shaped source spectra. Spurious structures caused by sidelobes can be eliminated in tomographic imaging and the performance of the tomographic system greatly improved. Detailed theoretical analysis is given. Both simulation and experimental results are presented to verify the idea. | The effects of gain guiding and thermal guiding on the cavity mode formation for quasi-three-level microchip lasers are investigated. A parameter describing the dominant guiding mechanisms at the lasing threshold is defined. Paraxial wave propagation equation for the field envelope in the gain medium with thermal-induced refractive index profile and gain profile is derived. A comparison between the calculated results and those of experiments reveals that this model is quite reasonable and applicable not only to the Yb:YAG microchip laser, but also to other quasi-three-level microchip lasers. | eng_Latn | 7,736 |
Effect of the thermal heating of a crystal on the diffraction of pulses of a free-electron X-ray laser | Spatiotemporal dependences of the distribution of the crystal temperature under the effect of pulses of a free-electron X-ray laser are found using the solution of a thermal conductivity equation. The effect of temperature, its gradient, and the deformation of the crystal lattice on the diffraction reflection and the transmission of pulses in crystals of synthetic diamond is considered. | Abstract Optical transmission loss changes upon curing the mixture of epoxy/ethylene diamine were studied A UV-Vis spectrum measured during the cure process was utilized to monitor both cure process and transmission loss change simultaneously. It was found that initial homogeneity of the epoxy/EDA mixture was the key parameter to determine the optical transmission of the cured epoxy Slow heating up to the curing temperature allowed the mixture homogenous, thus resulted in a structure of very low transmission loss. Subsequent curing rate was also another factor affecting the uniformity of the cured structure | eng_Latn | 7,737 |
Apparatus for compensating frequency offset and method thereof in orthogonal frequency division multiplexing system | There is provided an apparatus and method for compensating for a frequency offset in an orthogonal frequency division multiple)ing (OFDM system. In the frequency offset compensating apparatus, a correlating portion demodulates input data by fast Fourier transformation, delays a demodulated symbol by a predetermined period, and correlates a symbol demodulated during the delay to the delayed symbol. A pilot position detecting portion compares the correlation with a predetermined pilot position and e)tracts a correlation corresponding to the pilot position. A frequency offset compensating portion estimates a frequency offset to the e)tracted correlation if the e)tracted correlation is a predetermined ma)imum and shifts the phase of pilot data by the estimated frequency offset. | We report on experimental studies on the beam quality of the 8μm ZGP optical parametric oscillator(OPO). Through conducting a series of comparative experiments, the effects of resonator length, type of phase matching, resonant wavelength and structure of the resonator on the beam quality of ZGP OPO were studied respectively. By using longer resonator length(120mm), type I phase matching, longer resonant wavelength(8μm) and the ring cavity, the output with the beam quality factor of M2∼1.20 and 1.22 in the horizontal and vertical direction were achieved respectively. And this is a rather good beam quality level for 8μm ZGP OPO. | eng_Latn | 7,738 |
Design and performance evaluation of a compact, large-area PET detector module based on silicon photomultipliers | A PET module that comprises a pair of compact, high-resolution and large-area detectors based on silicon photomultipliers (SiPM) was developed and evaluated. The detector's effective area was 24 mm x 24 mm. LYSO crystals measuring 1.9 mm x 1.9 mm x 10 mm and charge division circuit were employed to obtain high spatial resolution with relatively concise Front-end electronics (FEE). Initial results showed the detector to be compatible with 1.5 T magnetic fields. The system's intrinsic FWHM spatial resolution is 1.50 mm. The average energy resolution is 18.5% and the coincidence timing resolution is 2.6 ns. (C) 2011 Elsevier B.V. All rights reserved. | We report the arbitrary modulation of chirped ultrashort laser pulses with a 70 GHz bandwidth. In the proof-of-principle experiment, modulation of Ti:sapphire laser emission was performed by the acousto-optic dispersive delay line, and the temporal pulse shape was measured with a picosecond streak camera. | eng_Latn | 7,739 |
Transmission spectrum of the Lyot filter | The improved method for calculating the Lyot filter parameters has been developed. The two-plate and three-plate Lyot ::: filters transmission spectra for the low threshold lasers tuned in the 1100-1300 nm spectral region are computed. | A new scheme for nonlinear image transfer with large-wavelength conversion and its possible applications for fine-line lithography are presented. The process uses a higher-order nonlinearity, and the coupled wave equations are solved in the lowest approximation that retains this nonlinearity. | eng_Latn | 7,740 |
Influence of External Fields and Environment on the Dynamics of Phase Qubit-Resonator System | We analyze the dynamics of a qubit-resonator system coupled with a thermal bath and external electromagnetic fields. Using the evolution equations for the set of Heisenberg operators that describe the whole system, we derive an expression for the resonator field, accounting for the resonator-drive, -bath, and -qubit interaction. The renormalization of the resonator frequency caused by the qubit-resonator interaction is accounted for. Using solutions for the resonator field, we derive the equation describing qubit dynamics. The influence of the qubit evolution during measurement time on the fidelity of a single-shot measurement is studied. The relation between fidelity and measurement time is shown explicitly. Also, an expression describing relaxation of the superposition qubit state toward its stationary value is derived. The possibility of controlling this state by varying the amplitude and frequency of drive is shown. | We evaluate the electric quadrupole moments of the ${^1}\!S_0$ and ${^3}\!P_0$ clock states of $^{27}$Al$^+$ and $^{115}$In$^+$. To capture all dominant contributions, our analysis extends through third order of perturbation theory and includes hyperfine coupling of the electrons to both the magnetic dipole and electric quadrupole moments of the nucleus. For $^{27}$Al$^+$, a fortuitous cancellation leads to a suppressed frequency shift. This should allow for continued improvement of the clock without special techniques to control or cancel the shift, such as the averaging schemes that are critical to other optical ion clocks. | eng_Latn | 7,741 |
Experimental demonstration of a simple method to engineer a single qutrit state with biphotons | Abstract A simple method to engineer qutrit state with biphotons is realized. The method is based on Hong–Ou–Mandel interferometer and it is insensitive to disturbance comparing to Mach–Zehnder interferometer in principle. Moreover, a tomography procedure is employed to reconstruct the output states. | The application of phase-shifting photoelasticity to real- time dynamic event involves simultaneous recording of the four phase-shifted images. This purpose is realized in this paper by using a special beam-splitting lens called Multispec Imager. The isoclinic and isochromatic parameters for a given time in a dynamic event are determined by using multi-load to phase-shifting technique. A modified median filter algorithm for wrapped phase data is also presented. | eng_Latn | 7,742 |
Low attenuation mode converter with modal power distribution controllability by twist processing in step-index optical fibers | We proposed a short-fiber-length mode scrambler that reproduces the equilibrium mode distribution of an A3e fiber. The mode scrambler is compact, mode-controllable and has low attenuation. It is effective for not only hard plastic-clad fiber but also all step-index fibers, such as all-glass and plastic optical fibers. | We have designed and demonstrated a chirped ladder-type tunable filter and discussed its potential application for a tunable diode laser. A ladder interferometric filter normally has a periodic passband, which makes it impossible to stabilize laser oscillation frequency. To overcome this drawback, we have designed, fabricated, and characterized a novel chirped tunable ladder filter. We have successfully demonstrated a single-passband response in the fabricated device. Furthermore, a tuning operation of more than 30 nm was achieved by introducing a current injection structure and optimizing electrode lengths at each single-stage ladder interferometer. | eng_Latn | 7,743 |
Electronic control of frequency converter sets for testing aircraft models | THE TESTING of airplane scale models in wind tunnels has brought about a demand for variable frequency a-c power for controlling the speed of power model motors used to drive the propellers of the plane models. To obtain aerodynamic data on the plane model which are equivalent to the expected performance of the actual plane, it is necessary to drive the model propellers at speeds greatly in excess of propeller speeds of the actual plane. During tests in the wind tunnel, it must be possible to control propeller speed and to measure accurately the speed as well as power input into the propeller. | Abstract : The first part of this report discusses a X-modulator, a powerful device in terms of optical computation, routing, and interconnection. The device is a 3 input, 3 output conservative and reversible switch, an optoelectronic Fredkin gate. Using arrays of these modulators, various reconfigurable switching, routing, and interconnection networks are constructed. The second part of this report discusses the high speed properties of vertical cavity modulators for optical interconnection and switching. The epitaxial structure, mask design, device processing and characterization of high speed vertical cavity resonant enhanced MQW modulators is described. | eng_Latn | 7,744 |
Insertion-loss-free 1/spl times/4 optical switch fabricated using bandgap-energy-controlled selective MOVPE | A 1/spl times/4 optical switch consisting of a passive 1/spl times/4 splitter and four laser diode amplifier gates was designed and fabricated using high-pressure bandgap-energy-controlled selective MOVPE. Insertion-loss-free operation with low injection current was achieved. | The paper presents recent developments in exact strip postbuckling analysis for anisotropic plates with combined in-plane loading and various in-plane edge conditions. The analysis improves the accuracy of the postbuckling mode ::: and the consequent prediction of stresses and strains in the postbuckling range. Plates are divided into longitudinal strips, for which the governing equilibrium equations are derived and solved analytically. Implementation of the ::: improved analysis into the exact strip software VICONOPT enables accurate stress distributions to be found for each stage of the postbuckling analysis. Numerical results are ::: presented and compared with previous results from VICONOPT and finite element analysis for validation. | eng_Latn | 7,745 |
Housing for an optoelectronic semiconductor component and semiconductor component | The invention relates to a housing (1) for an optoelectronic semiconductor component (10). The housing (1) comprises a housing body (2), a first connecting lead (31) and a second connecting lead (32), wherein the first connecting lead (31) and the second connecting lead (32) each extend in a vertical direction through the housing body (2). The invention further relates to a semiconductor component (10) having such a housing (1) and a semiconductor chip (6). | This thesis describes high-speed photodiodes in standard CMOS technology ::: which allow monolithic integration of optical receivers for short-haul communication. The electronics for (multiple users) long-haul communication is very expensive (InP, GaAs), but the usage is justified by the large number of users. For short distance communication, the number of users is small, and more cost-effective solutions were needed. An integrated optical receiver in standard CMOS technology is a viable candidate. | eng_Latn | 7,746 |
Generation and Direct Detection of Broadband Mesoscopic Polarization-Squeezed Vacuum | Using a traveling-wave optical parametric amplifier with two orthogonally oriented type-I BBO crystals pumped by picosecond pulses, we generate vertically and horizontally polarized squeezed vacuum states within a broad frequency-angular range. Depending on the phase between these states, fluctuations in one or another Stokes parameter are suppressed below the shot-noise limit. Because of the large number of photon pairs produced, no local oscillator is required, and 3 dB squeezing is observed by means of direct detection. | The authors consider the synthesis of arbitrary fibre-optic delay line filters using a modified Pade method. Although these are inherently positive systems, we show that filters with negative coefficients can be implemented by a suitable decomposition of their impulse response together with a differential photodetection scheme. | eng_Latn | 7,747 |
A laser Doppler velocimeter employing the laser as a mixer-oscillator | A laser Doppler velocimeter is described in which the laser is employed not only as a light source, but also as a mixer-oscillator, in order to give a simpler optical system. The efficiency is comparable to that of a con-ventional system, such as a Michelson interferometer, and coherence requirements do not impose very severe restrictions. The frequency response of the system is also considered. Measurements of the coherence and frequency response of the system are also given. | Abstract A new type of bifluorophoric molecule consisting of two heterocycle-linked coumarin fluorophors is studied. A high laser efficiency, a broad tunability range and good photostability for two synthesized biscoumarins are observed. One of the proposed biscoumarins covers the green spectral region where the efficiency of known laser dyes is relatively low. | eng_Latn | 7,748 |
A tunnel injection quantum dot comb laser with wideband emission spectra and temperature stability | A quantum dot comb laser with a 102 nm broad spectrum of emission and high temperature stability is demonstrated. | -We describe a simple method to generate wavelength-tunable pulses by using a semiconductor optical amplifier (SOA) as an intensity modulator and a gain medium. Wavelength tunable pulses at a repetition rate of 4.8 GHz have been generated. | eng_Latn | 7,749 |
The Genetics of Hyperkeratosis Lenticularis Perstans | Hyperkeratosis lenticularis perstans (HLP) occurred in three generations of the same family. The evidence presented favors the concept that HLP is a genodermatosis with a late onset and is transmitted by an autosomal dominant gene. | Two types of powerful, continuous action gas lasers are being most actively developed at the present time: the electrical discharged and the gas dynamic lasers. IVTAN research workers proposed a new method of generating laser beams - a magnetohydrodynamic method. As working fluid an MHDL may utilize a mixture of He + CO/sub 2/ with the addition of easily ionized atoms. The work conducted at IVTAN since 1970 is described. The preprint consists of two portions: the first is dedicated to the theoretical examination of MHDL: calculations of optimum lasing medium compositions, examination of various flow modes, calculations of amplification coefficient, and of MHD laser emission intensity. In the second part the results of the experimental studies of MHDL are discussed. The main result is that the lasing effect was obtained for the first time in an MHD laser. | eng_Latn | 7,750 |
Equilibrium control in the HBTX1C reversed field pinch | Abstract The horizontal position of the plasma in the HBTX1C reversed field pinch has been controlled to ± 1 mm by a feedback circuit. The plasma is moved to the desired position by momentarily closing either one of two semiconductor switches which alter the way in which current is shared by the parallel-connected field windings. Equilibrium control was added without the need for additional power supplies or additional field coils. | Abstract A simple method to engineer qutrit state with biphotons is realized. The method is based on Hong–Ou–Mandel interferometer and it is insensitive to disturbance comparing to Mach–Zehnder interferometer in principle. Moreover, a tomography procedure is employed to reconstruct the output states. | eng_Latn | 7,751 |
Aerodynamic characteristics of over/under inlet for turbine based combined cycle engine | To discuss the operating characteristics of the inlet which is used in Turbojet/Ramjet Combined Cycle engine at Mach 0 to 5,the profile of an "over/under" TBCC variable geometry inlet was given.Using CFD tools,the two-dimensional flow-field of the inlet was shown with properties of flow at different operating points.At every flight Mach number,the inlet can start without boundary layer suction.Based on the flow-field of cruise and transition states,the operating characteristics at different back pressure were analyzed.The result indicates that the back pressure at exit has effect on the performance of the inlet,especially at the transition state——change of back pressure between over and under exit can bring on aerodynamic coupling effects in the two ducts.The aerodynamic characteristic diagram varied with flight conditions of the inlet was presented.The factors affecting the performance of the inlet and the aerodynamic characteristics at typical flight conditions were analyzed. | We proposed a simple method to realize optical Fourier transform during the nonlinear wave shaping processes. In this method, an integrated optical superlattice is designed to realize multiple optical functions, which plays important roles in both the nonlinear harmonic generation process and the optical Fourier Transform process. We demonstrated our method by the nonlinear generation of Airy beams as an example. It is a universal method for beam shaping and is of practical importance for designing compact nonlinear optical devices. | eng_Latn | 7,752 |
Preparation and second-harmonic generation in Pb-doped oxide glasses | PbO-B 2 O 3 glasses were prepared by traditional melting method. XRD and optical spectra measurements were done ::: to check properties. Second-harmonic generation was observed in the glasses induced by thermal treatment and ::: thermally poling process, respectively. But second-harmonic generation intensity was normally larger for the ::: later, and it increased with increasing PbO content, poling voltage, temperature and time. The mechanism of ::: second-harmonic generation in the PbO-B 2 O 3 glasses was also discussed. A promising material for all-optical ::: switching devices is expected. | Abstract A simple method to engineer qutrit state with biphotons is realized. The method is based on Hong–Ou–Mandel interferometer and it is insensitive to disturbance comparing to Mach–Zehnder interferometer in principle. Moreover, a tomography procedure is employed to reconstruct the output states. | eng_Latn | 7,753 |
Optical-disk media fabrication for high data-transfer rate. | Two media fabrication methods are developed in order to improve the data-transfer rate of optical disks. One is a beam-scanning method for multispiral pregroove recording. A sixfold spiral pregroove with a 1.6-μm spacing can be recorded with this method. The other is a method for fabrication of phase-change optical-disk media that provides signal reading at 670 nm, writing at 830 nm, and high erasability at high linear velocity. The linear recording density of disks fabricated in this way is 1.2 times higher than that of optical disks read at 830 nm, and the erasability is more than 25 dB at 40 m/s. These methods offer the possibility of a data transfer rate 10 times higher than with conventional methods. | The TRANSMEDIA LITERACY project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no 645238 | eng_Latn | 7,754 |
Sol–Gel Synthesis of Silica Glasses, Doped with Nanoparticles of Cerium Oxide | A method is suggested for creating nanoparticles CeO2 incorporated into silica matrix using chemical modification of fumed silica surface with cerium acetylacetonate. A variant of the sol–gel method for synthesizing of silica glasses and optical composites containing nanoparticles of cerium oxide has been designed. Monolithic gels are produced on the basis of SiO2/CeO2, Si(OC2H5)4, and gelation catalyst (CH2)6N4. By the XRD, DTA, TG, photoluminescence, and measurements of specific surface area a research has been made into structural and physico-chemical properties of CeO2/SiO2 during the course of their thermal transformations up to formation of glasses. | Abstract In high performance polysilicon thin film transistors (TFTs) the uniformity of electrical characteristics remain a major problem. This situation has stimulated a growing activity aiming to control the lateral growth phenomenon. However, most of the techniques require additional processing steps or a rather high shot density. We present a technique based on a two-pass excimer laser crystallization process: during the first irradiation the sample is irradiated through a patterned mask, while the second irradiation, performed without the mask, results in the homogeneous crystallization of the sample. This technique allows the possibility of forming uniform polysilicon layers, with large (∼2 micron) and aligned grains, with a reduced number of shots and a relatively large process energy window. The results of crystallization performed at different laser energy densities, sample thickness and laser pulse duration are analyzed. | eng_Latn | 7,755 |
The role of plasma in the transfer of Escherichia coli cytokine-inducing substances across high-flux cellulosic membranes | It has been previously reported that the presence of plasma in the blood side compartment of cellulosic membranes enhances the transfer of cytokine-inducing substance (CIS) present in the dialysate compartment. This apparent enhancement could either be a result of (1) improved membrane permeability to CIS, (2) transfer of plasma components to the dialysate compartment thereby causing dissagregation of CIS with subsequent backtransfer to the blood compartment, or (3) improved detection of transferred CIS resulting from carryover of plasma from the blood compartment of the mononuclear cell incubation step | A new approach to the creation of a quantum cascade laser is suggested, which employs interband transitions in quantum wells with a coherent electron transport. The coherent electron transport is studied based on the simplest two-band Kane model, in which the interaction between states of the conduction and valence bands is described taking into account only states in the light hole subband of the valence band. | eng_Latn | 7,756 |
Simultaneous measurement of one- and two-photon excited fluorescence from a single sample: a detection method for oligonucleotides | A new method has been developed that is based on the use of a single-excitation wavelength from a cw laser to excite simultaneously one-photon and two-photon fluorescence (TPF). Fluorescence bands of a sample containing two oligonucleotides, one labeled with a one-photon fluorescence dye and the other with a TPF dye, can be measured simultaneously. The two fluorescence bands are well separated, because the one-photon excited fluorescence band is redshifted, whereas the TPF band is blueshifted from the excitation wavelength. The spectral separation was found to be as large as 200 nm when ADS 840NCS was used to label one oligonucleotide for one-photon fluorescence and Rhodamine Red-X dye was used for TPF. Spectral overlapping problem that plagues current DNA sequencing techniques can be eliminated effectively with this method. | Abstract : We have used an optical parametric oscillator (OPO) to characterize the fiber-optic cache-memory buffers. Prior to addition of the new OPO system, a home-built saturable-absorber mode locked erbium/ytterbium-fiber laser had been used in all our experiments. With the addition of a new OPO, we are able to remedy all prior deficiencies. The tunability represents the main advantage of the system to our research program, since the cache-memory buffers and regenerators that we are developing can be used at any wavelength. This is because the response of the fiber-optic parametric amplifier is wavelength independent; the fiber nonlinearity, which is responsible for the gain, exists at all wavelengths and is not restricted to the relatively narrow range of the erbium band (1.53-1.56 microns). Thus the OPO allows us to experiment in wavelength regions that have previously been inaccessible. | eng_Latn | 7,757 |
Electro-optic tuning of vacuum Rabi coupling in semiconductor quantum microcavity structures | Abstract Electro-optic tuning of vacuum Rabi coupling is demonstrated on a very high quality semiconductor quantum microcavity structure with reflectivity linewidths at resonance of 0.9 and 1.1 meV. The variation in energy of the reflectivity peaks as a function of electric field is fitted very well by a transfer matrix reflectivity (TMR) model, using an experimental determination of exciton oscillator strength, and hence exciton-photon coupling strength, with electric field. In high sensitivity photo-current experiments we obtain clear evidence for coupling to discrete excited and continuum exciton states. | Abstract A pre-existing plastic rabbit ear chamber was modified to be applicable for intravital-microscopic observations in pharmacological as well as pathophysiological studies on inflammation. The chamber consists of a base disk, a mica (or glass) cover-slip and a holder ring. The base disk has a round-table with a central protrusion in which a heat conductor of platinum wire is so implanted near the protrusion that thermal stimulation can be given to the regenerated tissue between the table and the coverslip. | eng_Latn | 7,758 |
ECT versus tricyclic antidepressants in depression: a review of the evidence. | The claim is often made that ECT is more effective and works more rapidly than antidepressant drugs in the treatment of depression. The author reviews the nine controlled studies comparing the two treatments that appear in the literature. All of the studies were methodologically deficient, especially concerning definition of depression, sample size, dose of drug, and statistical analysis. No conclusive answer is available to the question whether ECT is superior to antidepressants in the treatment of depression. Pivotal studies are needed. | High-performance electromagnetic susceptibility (EMS) for a 2.5Gb/s optical transceiver module is first demonstrated by polymer-based multi-wall carbon nanotubes (MWCNT). The EMS performance is experimental evaluated by the eye diagram and bit-error-rate test for a 2.5Gb/s lightwave transmission system. The plastic transceiver modules with the more weight percentage of the MWCNT exhibit a higher shielding effectiveness (SE), and hence show effective EMS performance, a better mask margin, and a lower power penalty. The MWCNT composites with SE are suitable for packaging low-cost and high-performance EMS optical transceiver modules used in fiber to the home (FTTH) lightwave transmission systems. | eng_Latn | 7,759 |
Stereoscopic construction and practice of optoelectronic technology textbook | It is a professional degree course textbook for the Nation-class Specialty—Optoelectronic Information Science and Engineering, and it is also an engineering practice textbook for the cultivation of photoelectric excellent engineers. The book seeks to comprehensively introduce the theoretical and applied basis of optoelectronic technology, and it’s closely linked to the current development of optoelectronic industry frontier and made up of following core contents, including the laser source, the light's transmission, modulation, detection, imaging and display. At the same time, it also embodies the features of the source of laser, the transmission of the waveguide, the electronic means and the optical processing methods. | This chapter contains sections titled: Introduction SONET Frames Virtual Tributaries STS-N Frames Maintenance Summary This chapter contains sections titled: References | eng_Latn | 7,760 |
Memory system for digital video and self-related to method for storing digital video data | A digital video (DV) memory system (700) comprises an interface module (702) which receives an incoming signal and the incoming signal into an incoming bit stream; a DV demultiplexer (704) directly to the interface module (702) is connected to receive the incoming bit stream, wherein the DV-demultiplexer (704) received blocks in the incoming bit stream into at least video blocks in video sections, and audio blocks in audio portions demultiplexed; and a memory (708) which is connected to the DV-demultiplexer (704) to store the video blocks and audio blocks. Due to the direct connection of the interface module (702) with the DV-demultiplexer (704) and in that the incoming bit stream is not out of the interface module (702) and the DV demultiplexer (704) is buffered, the request to the memory bandwidth to the memory (708) are significantly reduced and the interface module (702) and the DV demultiplexer (704) can easily be implemented together in a single IC. | This paper presents a gimbaled MEMS scanning mirror (MSM) especially developed for adaptive raster scanning in a ::: novel 3D ToF laser camera. Large quasi-static deflections of ±10° are provided by vertical comb drives in vertical ::: direction in contrast to resonant horizontal scanning of the 2.6x3.6mm elliptical mirror at 1600 Hz and 80° optical scan ::: range. For position feedback piezo-resistive position sensors are integrated on chip for both axes. To guarantee the full ::: reception aperture of effective 5 mm a synchronized driven MEMS scanner array - consisting of five hybrid assembled ::: MEMS devices - are used in a novel 3D ToF laser scanner enabling a distance measuring rate of 1MVoxel/s and an ::: uncertainty of ToF distance measurement of 3…5 mm at 7.5 m measuring range for a gray target. | eng_Latn | 7,761 |
Reconfigurable I/O interface for mobile equipments | Standardized I/O interfaces such as USB, E1A/T1A-232, PS/2, Ethernet, IEEE 1394, etc., gives us "High Connectivity" that means connections between different devices are guaranteed and users do not have to take care of the connections. However the standardized I/O interfaces are not optimized to all devices and various standards confuse users. We propose a novel I/O interface named Meta-I/O Interface in which reconfigurable LSIs such as FPGAs are used to solve these problems. In Meta-I/O Interface, peripheral devices, which are named Self-Informational Devices (SIDs), have individual non-volatile memories (ROMs) storing the I/O-circuit-configuration-data that are loaded in the FPGAs in the digital equipment through the common standardized connectors. The Meta-I/O Interface prototype is now under development and the circuit sizes are estimated using several current I/O interfaces. | We investigate the spatial quantum properties of the light emitted by a perfectly spatially degenerate optical parametric oscillator (self-imaging OPO). We show that this device produces local squeezing for areas bigger than a coherence are that depends on the crystal length and pump width. Furthermore, it generates local EPR beams in the far field. We show, calculating the eigenmodes of the system, that it is highly multimode for realistic experimental parameters. | eng_Latn | 7,762 |
Novel approach to fast determination of cholesterol oxidation products in Cypriot foodstuffs using ultra‐performance liquid chromatography‐tandem mass spectrometry | This paper reports the development and validation of a new method based on ultra-performance LC coupled to MS/MS for the simultaneous determination of four cholesterol oxidation products (COPs) in foodstuffs in only 4.1 min. The COPs were detected by ESI in positive-ion mode with multiple reaction monitoring, and the mass spectrometric conditions were optimized in order to increase sensitivity. The developed method was validated in terms of linearity, precision, LODs, and LOQs. Recoveries of the extraction process ranged from 86 to 98.5% when the samples were fortified at 100, 500, and 1500 ng/mL. The applicability of the method was confirmed by analyzing different food samples. Considering the paucity of data regarding the content of COPs in Cypriot foods, particular attention was devoted, for the first time, to the determination of the profile of the main COPs in widely consumed, traditional Cypriot foodstuffs (halloumi cheese, hiromeri, snails, etc.). | Abstract : We have used an optical parametric oscillator (OPO) to characterize the fiber-optic cache-memory buffers. Prior to addition of the new OPO system, a home-built saturable-absorber mode locked erbium/ytterbium-fiber laser had been used in all our experiments. With the addition of a new OPO, we are able to remedy all prior deficiencies. The tunability represents the main advantage of the system to our research program, since the cache-memory buffers and regenerators that we are developing can be used at any wavelength. This is because the response of the fiber-optic parametric amplifier is wavelength independent; the fiber nonlinearity, which is responsible for the gain, exists at all wavelengths and is not restricted to the relatively narrow range of the erbium band (1.53-1.56 microns). Thus the OPO allows us to experiment in wavelength regions that have previously been inaccessible. | eng_Latn | 7,763 |
An optical MEMS cross-bar switch | We present preliminary findings regarding an optical cross-bar switch concept based on integrated silicon photonics waveguides and a MEMS device. Finite difference time domain simulations were performed were performed at a wavelength of 1550 nm to validate the initial design. Simulations indicate that there is a 9 dB difference in output optical power that can be achieved between the two waveguides. | Most commercial cyclotrons intended for medical isotope production provide a limited number of beam ports crowded into a minimal vault space. Taking advantage of our new lab construction, we planned and installed a beam-line on port ♯2 of our GEMS PETtrace to bring beam to an additional 5 target positions. These are oriented in the vertical plane, with the downward directed beam well suited for molten target substrates. | eng_Latn | 7,764 |
Laser-induced fluorescence in the infrared from high-resolution Fourier transform spectroscopy | A comparison is made between stepwise and continuous scanning high-resolution Fourier transform spectrometers (HRFTSs) for the study of laser-induced fluorescence spectra of simple models in the infrared with a dense spectrum. The high-quality data show that the HRFTS is an excellent instrument for studying molecular structures from emission spectra. The stepwise instrument produces a better SNR in a given recording period. | We demonstrate an effective technique which allows one to characterize a small radius micro-ring resonator via low coherence interferometric measurement beyond light source bandwidth limitation. The experimental results show significant improvements in the extracted parameters. | eng_Latn | 7,765 |
High-performance photorefractive polymer operating at 1550 nm with near-video-rate response time | The development of a high-performance photorefractive polymer composite operating at 1550 nm is reported. We show 40% internal diffraction efficiency with response time of 35 ms and a net gain of 20cm−1 in four-wave mixing and two-beam coupling experiments, respectively. This is more than an order of magnitude improvement in the diffraction efficiency and net two beam coupling gain and two orders of magnitude in the response time than the previously reported photorefractive polymer operating at this technologically important wavelength. The improvement in photorefractive characteristics is accomplished by an enhanced orientation of the nonlinear optical chromophore in the present composite. | Abstract Transmission spectra of a photonic crystal resonator structure have been obtained where the Bragg dielectric mirrors contain a finite number of periods with an inverted order of layers and the resonator layer is made of a ferroelectric with a permittivity many times exceeding the permittivity of the layers in Bragg mirrors. Almost a complete transmission suppression was detected not only in the photonic band gap (except for a narrow region of the defect mode), but also outside the forbidden band. | eng_Latn | 7,766 |
Epifluorescence microscopic observation of monolayers of dipalmitolophosphatidylcholine: dependence of domain size on compression rates | Abstract A fluorescence microscopic technique was used to observe phase transitions in monolayers of DPPC. The sizes of the domain structures observed were found to be dependent on the rate of compression of the monolayer. The distribution of domain sizes for different rates of compression were unimodal, but the scatter in the sizes was greater during slow compressions. | We resolve the long standing controversy regarding the imaging by a planar lens made of left-handed media and demonstrate theoretically that its far field image has a fundamentally different origin depending on the relationship between losses {inside} the lens and the wavelength of the light $\lambda$. At small enough $\lambda$ the image is always governed by diffraction theory, and the resolution is independent of the absorption if both Im$\epsilon \ll 1$ and Im$\mu \ll 1$. For any finite $\lambda$, however, a critical absorption exists below which the superresolution regime takes place, though this absorption is extremely low and can hardly be achieved. We demonstrate that the transition between diffraction limited and superresolution regimes is governed by {the} universal parameter combining absorption, wavelength, and lens thickness. Finally, we show that this parameter is related to the resonant excitation of the surface plasma waves. | eng_Latn | 7,767 |
Quasi-static microscanner with linearized scanning for an adaptive 3D laser camera | This paper presents a gimbaled MEMS scanning mirror (MSM) especially developed for adaptive raster scanning in a ::: novel 3D ToF laser camera. Large quasi-static deflections of ±10° are provided by vertical comb drives in vertical ::: direction in contrast to resonant horizontal scanning of the 2.6x3.6mm elliptical mirror at 1600 Hz and 80° optical scan ::: range. For position feedback piezo-resistive position sensors are integrated on chip for both axes. To guarantee the full ::: reception aperture of effective 5 mm a synchronized driven MEMS scanner array - consisting of five hybrid assembled ::: MEMS devices - are used in a novel 3D ToF laser scanner enabling a distance measuring rate of 1MVoxel/s and an ::: uncertainty of ToF distance measurement of 3…5 mm at 7.5 m measuring range for a gray target. | Abstract A simple method to engineer qutrit state with biphotons is realized. The method is based on Hong–Ou–Mandel interferometer and it is insensitive to disturbance comparing to Mach–Zehnder interferometer in principle. Moreover, a tomography procedure is employed to reconstruct the output states. | eng_Latn | 7,768 |
ADIABATIC TRANSITION TRANSFER PHENOMENON OFELECTRONS AND THE QUANTUM STATISTICAL PROPERTIES OF LIGHT FIELD IN A KERR MEDIUM | AbstractWe first derive the state vector of a cascade three level atom interacting with pair coherent states in a kerr medium.It is shown by numerical calculations that the Kerr effect results in the adiabatic transition transfer phenomenon of electrons,and the superstructures in the long time behavior of the quantum statistical properties of light field appear. | Using the Stevens–Tiersten equation for slowly varying thickness modes in doubly rotated quartz plate piezoelectric resonators, we determine optimal electrode shape and size for these resonators. The electrodes obtained are optimal in that they satisfy Bechmann’s number in every direction. | yue_Hant | 7,769 |
Fiber lasers integration for LMJ | Abstract The Fibre-Injection System in the LIL–LMJ facilities makes use of a single-mode fiber based arborescent architecture. Starting from a unique single-mode oscillator, it consists of a high performance PM design which is dedicated to the generation of pulses onto a large number of synchronous outputs. The optical features to be optimised involve dynamic ranges in excess of 50 dB and the generation of 25 ns wide arbitrary waveforms at 100 ps time resolution, of which the PSD looks like a precisely controlled Bessel distribution. We analyse the complete design issues, together with the optical components which have been developed specifically. To cite this article: A. Jolly et al., C. R. Physique 7 (2006). | The frequency characteristics of Josephson own radiation have been studied by means of Fourier spectroscopy. The FIR measurements were performed with the help of Fourier spectrometer coupled with the Nb Josephson junction. The main feature of this technique is that one Josephson junction operates as both generator and detector of own radiation at the same time. The spectrometer operates either in double-beam mode with resolution /spl sim/2 GHz or in multi-beam mode with resolution /spl sim/1 GHz. > | eng_Latn | 7,770 |
ICPD: an SOI-based photodetector with high responsivity and tunable response spectrum | A novel photodetector based on a silicon-on-insulator (SOI) substrate is demonstrated experimentally in this work. The device uses the interface coupling effect in an SOI transistor structure to amplify the photocurrent, and thus achieves extremely high responsivity up to 6×104 A/W. The responsivity of the device under ultraviolet (UV) light is much higher than that under visible and near-infrared light, which implies potential application in visible-blind UV detection. Furthermore, a MoS 2 gate is combined with the SOI-based photodetector to tune the response spectrum and shift it to the near-infrared band. With high reponsivity and tunable response spectrum, the ICPD device can find many interesting applications. | Codes with traceability properties are used in schemes where the identification of users that illegally redistribute content is required. For any code with traceability properties, the Identifiable Parent Property (c-IPP) seems to be less restrictive than the Traceability (c-TA) property. In this paper, we show that for Reed-Solomon codes both properties are in many cases equivalent. More precisely, we show that for an [n,k,d] Reed-Solomon code, defined over a field that contains the n − d roots of unity, both properties are equivalent. This answers a question posted by Silverberg et al. in [10,11], for a large family of Reed-Solomon codes. | eng_Latn | 7,771 |
Achieving publication excellence in the Journal of the Acoustical Society of America | Publications in refereed acoustics journals are of significant relevance for scientists and engineers in acoustics-related fields. The Journal of the Acoustical Society of America (JASA) encourages authors to submit papers to JASA for publication. JASA regularly publishes detailed updated guidelines and instructions in order to help potential authors achieve publishing excellence. As a frequent reviewer, an author of JASA papers, and an Associate Editor of JASA, this author will provide an outline and overview of the JASA peer-review process in order to clarify the standards used to assess both successful and unsuccessful publication efforts. This author also discusses how to prepare qualified manuscripts, how to avoid unnecessary delays for, and how to review manuscripts for JASA. | We review recent methods to increase the speed of the nonlinear optical response of semiconductor optical amplifiers (SOAs), including the use of filters and of an additional SOA in the 'turbo-switch' configuration. We also consider the effects of optimising parameters, such as the confinement factor and optical area, on the recovery rate. | eng_Latn | 7,772 |
Influence of vibrational relaxation on the quantum efficiency of a KrF excimer laser | A theoretical analysis is made of the kinetics of electronic–vibrational relaxation of excimer molecules in the active medium of a KrF laser. Equations are derived to describe the dependence of the lasing quantum efficiency on the photon flux in the resonator, on the mechanism of formation of electronically excited molecules, and on the composition of the active gas mixture. | The generation and behavior of the fractal Koch array factor from a Kaiser window generator is studied. The main advantage of using Kaiser windows is that pattern parameters become much more flexible through altering the Kaiser window. The mainlobe width, current distribution, side-lobe ratio are now adjustable. Different reduced array structures can be obtained by using different threshold levels. Higher threshold values result in a highly reduced number of elements but they may highly distort the pattern and, hence, the multiband behavior. Finally, we study the effect of quantization of the feeding values. Quantization is necessary for implementation and simplification purposes. Several configurations of current distributions with the corresponding patterns are illustrated for different quantization levels. It is shown that moderate quantization keeps the same interesting similarity properties at several bands. | eng_Latn | 7,773 |
WDM fiber laser source using loop mirror configuration | A novel, simple, and flexible WDM laser source is demonstrated using a loop erbium-doped fiber amplifier. Two configurations of the source are investigated where reflecting FBGs are cascaded in series or parallel at the loop outputs. High output power per channel with a signal-to-noise ratio better than 55 dB can be achieved. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 187–189, 2001. | We analyze different families of discrete maps\ in the N-qubit systems in the context of the permutation invariance. We prove that the tomographic condition imposed on the self-dual (Wigner) map is incompatible with the requirement of the invariance under particle permutations, which makes it impossible to project the Wootters-like Wigner function into the space of symmetric measurements. We also provide several \textit{explicit} forms of the self-dual mappings: a) tomographic and b) permutation invariant \ and analyze the symmetric projection in the latter case. | eng_Latn | 7,774 |
Photodiode nonlinearity measurement using a linearized phase-modulated optical link | A new technique to determine the nonlinearity of high-speed photodiodes is presented. Utilizing a linearized phase-modulated link architecture, we directly measure the photodiode intermodulation distortion. Our results agree with those obtained via a phase-locked laser technique. | The invention discloses a plasma electrolytic oxidation automate control device and method that includes the following steps: putting the processing material as anode into silicate solution and connects to the two poles of AC power supply with cathode material through wire, the signals collected from current sensor and voltage sensor would be sent to computer to take process, and the processing result would be sent to PWM controlling device, which would adjust the wide of negative and positive pulse, and ensure the current density constant on sample. Ceramic plating made from the method wouldhave stable capability and the labor intention would be decreased. | eng_Latn | 7,775 |
Communication Ring Initialization without Central Control | Abstract : This short memorandum describes a novel combination of three well-known techniques; the combination provides a systematic way of initializing a local-area ring network without previous, static designation of a distinguished station. The result is a distributed algorithm that dynamically designates a distinguished station from among a group of stations whose ability to communicate is hampered by the fact that the ring is not yet initialized. An appendix describes how this approach could be implemented as part of the 10/ Megabit/second (version 2) ring network currently being installed at the MIT laboratory for Computer Science. (Author) | We introduce a class of critical states which are embedded in the continuum (CSC) of one-dimensional optical waveguide array with one non-Hermitian defect. | eng_Latn | 7,776 |
Midinfrared emission from near-infrared quantum-dot lasers | We report the electrically pumped emission of midinfrared (MIR) radiation from bipolar quantum-dot lasers during near-infrared lasing. The MIR spectrum exhibits a peak at 16 μm and is dominantly TM polarized. The MIR intensity exhibits a superlinear dependence on the injection; a maximum MIR power of 0.1 μW per facet was realized. Such a device is also modeled theoretically, and conditions for MIR lasing are predicted. | Abstract A simple method to engineer qutrit state with biphotons is realized. The method is based on Hong–Ou–Mandel interferometer and it is insensitive to disturbance comparing to Mach–Zehnder interferometer in principle. Moreover, a tomography procedure is employed to reconstruct the output states. | eng_Latn | 7,777 |
PID Parameters Auto-tuning Based on PLC | PID controllers are widely used in process industry.But the control quality of PID loops operating is different in industrial fields and many of them have to be switched to manual mode.Some of them are attributed to process dynamics characteristics which make PID tuning be unsatisfied to control requirements,but some are due to poor turing of PID parameters.In light of the tediousness and difficulty of PID tuning,an auto-tuning method based on PLC is adopted to ease the procedure.The adopted PID auto-tuning is simple in theory,easy to conduct and it is satisfied in a constant pressure water supply system.Based on relay feeedback auto-tuning,this method can be easily applied to other processes. | -We describe a simple method to generate wavelength-tunable pulses by using a semiconductor optical amplifier (SOA) as an intensity modulator and a gain medium. Wavelength tunable pulses at a repetition rate of 4.8 GHz have been generated. | eng_Latn | 7,778 |
Measurement of the quantum yield of triplet formation and short triplet lifetimes by the transient grating technique | A transient grating method for measuring the quantum yield of triplet formation (Φisc) and lifetimes of short‐lived triplet states is proposed. The method is based on a measurement of time dependence of a thermal grating signal with a nanosecond pulsed laser and a cw probe laser. The validity of the method is demonstrated by determining Φisc of a number of molecules whose Φisc are known. Advantages and limitations of this method are discussed in detail. | The design of the LTE physical layer (PHY) is heavily influenced by the requirements for high peak transmission rate (100 Mbps DL/50 Mbps UL), spectral efficiency and multiple channel bandwidths (1.25–20 MHz). Unfortunately, the existing WCDMA turbo interleaver does not permit an efficient high throughput implementation. That is why the 3rd Generation Partnership Project (3GPP) has proposed the quadratic polynomial permutation (QPP) interleaver to rectify this situation. In this paper, we will study the performances of QPP interleaver for LTE encoder channel for different configurations of LTE system and we study the effect of LTE channel turbo encoder for the transmission over a wireless multipath channel. | eng_Latn | 7,779 |
Semiconductor InGaAs/GaAs injection lasers with waveguides based on a single quantum well | Semiconductor InGaAs/GaAs injection lasers emitting at λ = 1065 nm have been created with waveguides based on a single InGaAs quantum well. It is found that internal optical losses are determined by the width of an undoped region confined between the n and p type emitters. The room-temperature total output optical power in lasers with 100 μm aperture amounted up to about 2 W at a radiation beam divergence of 15° in the plane perpendicular to the p-n junction. | We report fabrication of GaN microrods and their intracellular lasing characteristics for individual cell tracking and labeling application. © 2019 The Author(s) | eng_Latn | 7,780 |
Solar controller driving 50W LED | Photovoltaic power generation technology is already quite mature. But the conversion efficiency of the silicon cells which are heavily used now remains stagnant. Besides, large amounts of energy will be consumed during the process of production. It also makes serious pollution. Thus, to maximize utilization of solar cells will undoubtedly have a huge problem about economic and environmental benefits. LED has high luminous efficiency and is the ideal lighting source. It is supplied by the DC power. Combining solar power technology and LED lighting technology can save solar grid inverters, switching power supplies and many other necessary devices for grid-connected power generation, which increases the efficiency of solar cells and reliability, saves fossil energy and reduces environmental pollution. This paper introduces an controller combining solar power generation technology and LED lighting technology. | The computer controlled Laserthermia system by the method of using double ::: channel endoscope with the contact frosted probe and a thermocouple was reported ::: previously.25 In this paper, the single channel method with the new single ::: laser delivery system was studied experimentally. Especially hyperthermal effect ::: by the newly developed Hybrid Laserthermia feedback probe(Hybrid probe) was discussed ::: comparatively with the effects by the interstitial contact probe. The Hybrid ::: probe could be possible to treat clinically more accurate Laserthermia in ::: the near future. | eng_Latn | 7,781 |
Emergence of Classical Radiation Fields through Decoherence in the Scully± Lamb Laser Model | The quantum theory of the laser of Scully and Lamb is used to determine the longest-lived states of the quantized field in an idealized, single-mode laser cavity. It is shown that quasiclassical states (states with well-defined phase and amplitude) are naturally selected. A quantum trajectory analysis provides some insight as to why this is so. | This paper presents design and characteristics of a compact, highly integrated Ka-band T/R module built by using a miniature magnetron in the transmitter chain. By implementing a solid-state modulator and microstrip design in the microwave part of the receiver, the overall size of the module has been reduced significantly. The module provides capabilities to realize Doppler date processing by using a digital coherent-on-receiver technique. | eng_Latn | 7,782 |
Photochemistry of biological molecules--V. A mechanistic study of the photolysis of cycloalanylalanine in the solid state. | — Earlier studies of the photodamage induced by 254 nm irradiation of linear alanine peptides in the solid state have been supplemented by an investigation into the gaseous photoproducts from the cyclic dipeptide, 3,6-dimethyl-2,5-diketopiperazine. The trans and cis isomers have been prepared and the photoproducts compared with those from the DL-mixture. The conformation of the molecule does influence the yield of gaseous products. CO was produced by peptide bond rupture with concomitant release of hydrogen. CO2 was also produced. The use of N- and C-deuterated analogues together with relevant crystallographic and EPR data has enabled a detailed study of the mechanism of photode-gradation to be made, from which it is concluded that the methyl protons are not inert but rather are the major source of the hydrogen observed on photolysis. | For large-scale, multi-partite photonic quantum information system, stable on-demand single photon sources are particularly important building blocks. A scheme to implement the source is to multiplex many heralded single photon sources of identical photon pair generators. To achieve this, we must increase the integration density of the photon pair generators. Slow light enhanced nonlinearity in Si photonic waveguides has proven useful for reducing the device size. So far, we demonstrated that coupled-resonator optical waveguides (CROWs) based on photonic crystal (PhC) nanocavities exhibited the largest nonlinear constant γ (/W/m) in Si-core waveguides thanks to the slow light enhancement and a strong spatial field confinement achieved by PhC nanocavities. Using the PhC-cavity-based CROW, we demonstrate efficient correlated photon pair generation. | eng_Latn | 7,783 |
Detection and Localization of Methionine Sulfoxide Residues of Specific Proteins in Brain Tissue | Methionine sulfoxide is a common posttranslational oxidative modification that can alter protein function. Vul- nerability of specific proteins to methionine oxidation varies and depends on their structure. In the current study, detection of methionine sulfoxide in intact proteins is mediated by novel anti-methionine sulfoxide antibody that resulted in the identification of three major methionine sulfoxide-proteins in brain: bisphosphate aldolase A and C, � andsubunits of hemoglobin, and serum albumin. The locations of the methionine sulfoxide residues were determined by mass- spectrometry analyses. It is suggested that the in vivo methionine oxidation of these proteins represent early posttransla- tional oxidative modification of proteins in brain. Thus, elevated levels of methionine-sulfoxide in these proteins may serve as bio-markers for enhanced oxidative stress in brain, which may be associated with brain disorders and diseases. | This paper presents a gimbaled MEMS scanning mirror (MSM) especially developed for adaptive raster scanning in a ::: novel 3D ToF laser camera. Large quasi-static deflections of ±10° are provided by vertical comb drives in vertical ::: direction in contrast to resonant horizontal scanning of the 2.6x3.6mm elliptical mirror at 1600 Hz and 80° optical scan ::: range. For position feedback piezo-resistive position sensors are integrated on chip for both axes. To guarantee the full ::: reception aperture of effective 5 mm a synchronized driven MEMS scanner array - consisting of five hybrid assembled ::: MEMS devices - are used in a novel 3D ToF laser scanner enabling a distance measuring rate of 1MVoxel/s and an ::: uncertainty of ToF distance measurement of 3…5 mm at 7.5 m measuring range for a gray target. | eng_Latn | 7,784 |
Electronic energy dissipation in chloro-aluminum phthalocyanine/methanol system following nonlinear interaction with a train of picosecond pulses | Using the Z-scan technique, we study the nonlinear interaction of a dilute methanolic solution of chloro-aluminum phthalyocyanine with a ∼70 ns long train of laser pulses, each of 18 ps duration. The observations are explained by taking into account, in addition to the photoexcitation of a ground state molecule by a single pulse, thermal lensing and photoabsorption by an excited molecule (singlet or triplet) produced by previous pulses. A microscopic picture of the heating process in the solution is provided. | An approach for modeling of planar microwave filters by the Method of Lines (MoL) is presented. The algorithm combines 2-D discretization of the cross-section with the numerically stable impedance/admittance transformation. To improve accuracy and efficiency of this approach, edge conditions are examined and the best edge position relative to the discretization lines is derived. The convergence behaviour of the method for different edge positions is examined. To substantiate the proposed formulation three planar microwave filter are modeled. | eng_Latn | 7,785 |
Experimental Demonstration of the Doppler Frequency Conversion in a Slot Line | Frequency conversion from microwaves to millimetre waves using the Doppler effect in a slot line on an optically excited silicon-on-insulator (SOI) substrate has been experimentally demonstrated. Laser pulses with a wavelength of 532 nm and duration of 33 psec have generated electron-hole plasma periodically at the intervals of 1.2 mm and of 13.6 psec on the SOI surface along the slot line. The plasma acts as an rf-short which effectively moves at a relativistic velocity. The rf-short reflects counter propagating microwaves and up-shifts their frequency through the double Doppler effect. Experiments have shown that microwaves at the frequencies between 10 GHz-18 GHz in the slot line have been successfully converted to millimetre waves with a frequency up-ratio of about 3.9. | The University of Newcastle, New South Wales, AustraliaA technique for monitoring and detecting change in a time series of physiologicalobservations is described. The method uses an optimal linear estimator—theKalman niter—to predict future observations of the series and a random walktraversed by the residuals from the estimation process to detect changes in theparameters of the time series. A computer algorithm and an example of itsapplication in heart-rate monitoring are presented. | eng_Latn | 7,786 |
Visible Light Communication System Using an Organic Bulk Heterojunction Photodetector | A visible light communication (VLC) system using an organic bulk heterojunction photodetector (OPD) is presented. The system has been successfully proven indoors with an audio signal. The emitter consists of three commercial high-power white LEDs connected in parallel. The receiver is based on an organic photodetector having as active layer a blend of poly(3-hexylthiophene) (P3HT) and phenyl C61-butyric acid methyl ester (PCBM). The OPD is opto-electrically characterized, showing a responsivity of 0.18 A/W and a modulation response of 790 kHz at −6 V. | For an emerging market a mass and cost-effective production of non-silicon micro devices requires an in-process and accurate 3D monitoring to assure the quality. Optical coherence tomography (OCT) ... | eng_Latn | 7,787 |
Oscillator circuits for wide-range tuning | The design and operation of circuits to cover wide tuning ranges at ultra-high frequency, when used in conjunction with triode valves of the disc-seal type, are described in detail. The use of coaxial-line resonators to cover various tuning ranges between frequencies of about 300 Mc/s and 3750 Mc/s, and the practical difficulties encountered with such circuits, are discussed. Alternative forms of circuits which overcome most of the problems involved have been developed and details are given of oscillator units which cover wide ranges up to frequencies of the order of 1200 Mc/s. | -We describe a simple method to generate wavelength-tunable pulses by using a semiconductor optical amplifier (SOA) as an intensity modulator and a gain medium. Wavelength tunable pulses at a repetition rate of 4.8 GHz have been generated. | eng_Latn | 7,788 |
Modulated beating signal generation via bias modulations of micro-heaters integrated on dual-mode laser | A simple and compact method of generating modulated beating signals from a dual-mode laser via bias modulation of integrated micro-heaters is proposed and successfully demonstrated. The proposed scheme will enrich the continuous-wave terahertz system applications. | Controlling spatiotemporal chaos in excitable media by applying low-amplitude perturbations {\em locally} is of immediate applicability, e.g., in treating ventricular fibrillation, a fatal disturbance in the normal rhythmic functioning of the heart. We look at a mechanism of control by the local application of a series of biphasic pulses, i.e., involving both positive and negative stimulation. This results in faster recovery of the medium, making it possible to overdrive the chaos by generating waves with frequency higher than that possible with only positive pulses. This provides the simplest and most general understanding of the effectiveness of biphasic stimulation in controlling fibrillation and allows designing optimal waveshapes for controlling spatiotemporal chaos. | eng_Latn | 7,789 |
Channelrhodopsin Photochromic Reactions Provide Multicolor Optogenetic Control | In this issue of the Biophysical Journal, Venkatachalam and Cohen (1) present an innovative combination of opsin-based optogenetic voltage control with simultaneous imaging of green fluorescent protein (GFP)-based sensors. The challenge is that the overlapping absorption spectra of GFP derivatives and the commonly used blue-light activated ChR2-based channelrhodopsins prevent photoactivation of neuron firing without simultaneously perturbing the fluorescent reporter. The authors elegantly circumvent this overlap by taking advantage of the color-sensitive photoreactions of spectral intermediates of ChR2. An interesting twist is that in the “stoplight” technique that they developed, optical engineering creatively mimics nature. Evolution produced a mechanism using the same principle to enable color-discriminating motility responses mediated by the phototaxis receptor sensory rhodopsin I in haloarchaea. | Abstract : We have used an optical parametric oscillator (OPO) to characterize the fiber-optic cache-memory buffers. Prior to addition of the new OPO system, a home-built saturable-absorber mode locked erbium/ytterbium-fiber laser had been used in all our experiments. With the addition of a new OPO, we are able to remedy all prior deficiencies. The tunability represents the main advantage of the system to our research program, since the cache-memory buffers and regenerators that we are developing can be used at any wavelength. This is because the response of the fiber-optic parametric amplifier is wavelength independent; the fiber nonlinearity, which is responsible for the gain, exists at all wavelengths and is not restricted to the relatively narrow range of the erbium band (1.53-1.56 microns). Thus the OPO allows us to experiment in wavelength regions that have previously been inaccessible. | kor_Hang | 7,790 |
Design and analysis of high speed uni-traveling-carrier photodiodes | In this paper, simulations are conducted to investigate high speed uni-traveling-carrier photodiodes (UTC-PDs). The Gaussian doping profile, which can introduce potential gradient and electric field, is presented to be used in the absorption layer. Compared to constant doping and step-graded doping, bandwidth of UTC-PD with Gaussian doping is improved substantially. | Abstract We have considered, a photon transport problem for two configuration types often encountered in nuclear geophysics. The usual Monte Carlo algorithm was modified so that the photon trajectories were constructed with the aid of uniformly distributed LP τ sequences and their length were restricted. An improvement in the rate of convergence was achieved and the truncation error was estimated. An attempt was made to compare numerically the rate of convergence of the modified algorithm and the usual Monte Carlo that uses pseudo-random numbers. | eng_Latn | 7,791 |
Frequency Modulation Of Short Laser Pulses As A Method Of Image Transfer | It is shown, that the Fourier-processing based modulation of short laser pulses can be successfully used for all-optical image transfer. The proposed system contains a transmitter, where the transferred image modulates the frequency profile of the carrier pulse, and a receiver, where after the reverse processing is restored the original image. The main limitations are discussed. The transfer of binary amplitude and phase images is demonstrated. | Optic characteristics of breast tissues have been examined in mothers. An internation was designed to prevent and treat nipple fissures using individualized laser therapy regimens. Individualized laser therapy of 329 mothers at risk of mastitis and 68 mothers with a normal postpartum course reduced five-fold the incidence of mastitis in the risk group (from 18.6% to 3.7%, or to values characteristic of a normal puerperium). The wave length of 0.63 micron was found to be of a higher preventive and therapeutic efficacy, compared to the wave length of 0.89 micron. Laser rays activated the immune system, as reflected by rising serum levels of immunoglobulins A, M, G and lactoferrin. It is suggested that mothers with high trophoblastic beta-glycoprotein concentrations are at high risk of puerperal septic complications. | kor_Hang | 7,792 |
Screening charge distribution in pockels readout optical modulators | A voltage is applied through semitransparent electrodes on either side of the structure and then the photoconductor is explosed to light. The photocarriers drift to the photoconductor-dielectric interface under the influence of the applied external field. As a result, an interface charge distribution corresponding to the write-in image light distribution, and screening the field in the photo-conductor is formed | We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation ::: dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion ::: managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked ::: spectra with a smooth and well-behaved spectral phase. A very good agreement with experimental measurements ::: of pulse energy, spectrum, and temporal width of extracavity compressed pulses is found. | eng_Latn | 7,793 |
Effect of deep placement of controlled release nitrogen fertilizer (coated urea) on growth, yield, and nitrogen fixation of soybean plants | Abstract The objective of these studies is to increase the productivity of soybean [Glycine max (L.) Merr. cv. Enrei] with good quality by the application of controlled release nitrogen fertilizers. Soybean was grown in an upland field converted from a drained paddy field in Niigata. The fertilizer treatments were as follows: (a) control, conventional basal dressing of ammonium sulfate (16 kg N/ha); (b) deep placement, deep placement of coated urea, 100 day type (100 kg N/ha) with basal dressing of ammonium sulfate (16 kg N/ha); (c) top dressing, top dressing of coated urea, 70 day type (100 kg N/ha) just before the flowering stage with basal dressing of ammonium sulfate (16 kg N/ha). We employed the following methods and materials: “15N-labeled fertilizers,” to estimate the amount of N derived from fertilizers; “N-balance method” using the nodulating and non-nodulating isogenic line cv. T202 and T201, to estimate the amount of fixed N2 by root nodules; “relative ureide method” to determine the relative c... | Abstract CW-pumped Nd:YVO 4 lasers passively Q-switched with LiF : F 2 - and YAG:Cr 4+ saturable absorbers are modeled and comparatively analyzed. The model takes into account the geometric factor representing the distributions of the orientations of F 2 - color centers and Cr 4+ ions relatively to the corresponding crystalline hosts on the output parameters of the lasers. It is shown that the LiF : F 2 - Q-switch has evident advantages over the YAG:Cr 4+ one in the senses of a much more expanded range of pump powers where the giant-pulse regime is supported in the laser and, as a consequence, potentially higher average output and peak pulse powers accessible. | eng_Latn | 7,794 |
Manufacturing PDMS micro lens array using spin coating under a multiphase system | The development of micro lens arrays has garnered much interest due to increased demand of miniaturized systems. Traditional methods for manufacturing micro lens arrays have several shortcomings. For example, they require expensive facilities and long lead time, and traditional lens materials (i.e. glass) are typically heavy, costly and difficult to manufacture. In this paper, we explore a method for manufacturing a polydimethylsiloxane (PDMS) micro lens array using a simple spin coating technique. The micro lens array, formed under an interfacial tension dominated system, and the influence of material properties and process parameters on the fabricated lens shape are examined. The lenses fabricated using this method show comparable optical properties—including surface finish and image quality—with a reduced cost and manufacturing lead time. | The method of quantum trajectories is adopted to the problem of laser generation with variable number of active media atoms in the cavity. The approach is applied to an injection-locked sub-Poissonian laser. The onset of laser oscillations is studied for the case of simultaneous start of the injection and pumping. It is shown that in this case the generation regime reached, where the intra-cavity intensity goes down with increasing the synchronization. | eng_Latn | 7,795 |
Electrochemical behavior of hemoglobin in neutral surfactants with different poly(ethylene oxide) unit lengths adsorbed on an electrode | The direct electron transfer and adsorption behavior of hemoglobin (Hb) in a series of surfactants with different poly(ethylene oxide) (PEO) unit lengths on a glassy carbon electrode have been studied. With a surfactant of appropriate PEO unit length, the surfactant film-modified electrode exhibited a more stable adsorption state with a larger surface coverage of Hb and a more positive formal potential, which can be attributed to the effect of hydrogen bonding between proteins and surfactants. The electrochemical behavior of surfactants with different PEO unit lengths is discussed in detail. Moreover, UV-visible spectroscopy demonstrated that the structure of Hb was not destroyed in the surfactant films. The electrocatalytic activity of hydrogen peroxide on three neutral surfactant-modified electrodes has also been investigated. | Abstract : We have used an optical parametric oscillator (OPO) to characterize the fiber-optic cache-memory buffers. Prior to addition of the new OPO system, a home-built saturable-absorber mode locked erbium/ytterbium-fiber laser had been used in all our experiments. With the addition of a new OPO, we are able to remedy all prior deficiencies. The tunability represents the main advantage of the system to our research program, since the cache-memory buffers and regenerators that we are developing can be used at any wavelength. This is because the response of the fiber-optic parametric amplifier is wavelength independent; the fiber nonlinearity, which is responsible for the gain, exists at all wavelengths and is not restricted to the relatively narrow range of the erbium band (1.53-1.56 microns). Thus the OPO allows us to experiment in wavelength regions that have previously been inaccessible. | eng_Latn | 7,796 |
Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL | The Electro-optical sampling delay scanning technique can be used for electron beam bunch length measurement.A novel non-synchronous delay scanning technique based on the electro-optical sampling measurements is presented.Based on Beijing Free Electron Laser(BFEL),the electron beam bunch length was ... | This paper proposes a strategy to determine how much a given network can affect the QoS parameters of another, by interference. In order to achieve this, a measurement campaign was carried out in two stages: firstly with a single AP and later with two APs separated by a distance less than three meters, using the same channel. After the measurement, an analysis of the results and a set of inferences were made by using Bayesian Networks, whose inputs were the experimental data, i.e. QoS metrics such as: throughput, jitter, packet loss, PMOS and physical metrics like power and distance. | eng_Latn | 7,797 |
Quasi phase matching in GaAs–AlAs superlattice waveguides through bandgap tuning by use of quantum-well intermixing | We report the observation of second-harmonic generation by type I quasi phase matching in a GaAs-AlAs superlattice waveguide. Quasi phase matching was achieved through modulation of the nonlinear coefficient chi((2))(zxy), which we realized by periodically tuning the superlattice bandgap. Second-harmonic generation was demonstrated for fundamental wavelengths from 1480 to 1520 nm, from the third-order gratings with periods from 10.5 to 12.4microm . The second-harmonic signal spectra demonstrated narrowing owing to the finite bandwidth of the quasi-phase-matching grating. An average power of ~110 nW was obtained for the second harmonic by use of an average launched pump power of ?2.3mW . | In this paper, a novel optimization algorithm, termed genetic local search algorithm (GLSA), that combines a genetic algorithm (GA) with a local search technique is proposed to design DOE's. This hybrid algorithm performs an improved, more goal-oriented search compare to a purely GA. A 1:17 cross pattern fan out grating and a uniform focal plane intensity profile generator are designed to demonstrate the algorithm we proposed. Numerical results proved that the proposed algorithm are highly robust and efficient. High-quality DOE's are achieved by using the algorithms we proposed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | eng_Latn | 7,798 |
Novel Quinidine-Derived Organocatalysts for the Asymmetric Substitutions of O-Boc-Protected Morita–Baylis–Hillman Adducts | A series of novel quinidine-derived organocatalysts was synthesized and utilized for the asymmetric substitution of O-Boc-protected Morita–Baylis–Hillman adducts with various carbamates and tosylcarbamates, affording the corresponding products in good to high yields (up to 91 % yield) with moderate to high ee values (up to 96 % ee) under mild conditions. | Abstract A laser–diode-pumped passively Q-switched new type crystal Nd 3+ :NaY(WO 4 ) 2 (known as Nd:NYW) laser with GaAs semiconductor saturable absorber has been realized. The dependence of pulse repetition rate, pulse energy, pulse width, and peak power on pump power for different output coupler reflectivities are measured. The coupled rate equations are used to simulate the Q-switched process of laser, and the numerical solutions agree with the experimental results. | eng_Latn | 7,799 |
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