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Infrared and near infrared transient absorption spectroscopy of molecular free radicals | Recent results obtained using absorption techniques with continuous wave lasers to measure vibrational and electronic spectra of small free radicals are reported.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | A new structure, suitable for implementing narrow as well as moderately wide transition band FIR filters, is presented. The proposed structure leads to a saving of 20 – 40% in the number of multipliers for moderately wide transition band filters. The saving for the narrow transition band filter increases with decreasing transition width. | eng_Latn | 7,900 |
Role of nitrogen in photoluminescence up-conversion in GaInNP/GaAs heterostructures | Alloying of disordered GaInP with nitrogen is shown to lead to very efficient PLU in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy (GS‐MBE). This is attributed to the N‐induced changes in the band alignment at the GaInNP/GaAs heterointerface from the type I for the N‐free structure to the type II in the samples with N compositions exceeding 0.5%. Based on the performed excitation power dependent measurements, a possible mechanism for the energy upconversion is suggested as being due to the two‐step two‐photon absorption. The photon recycling effect is shown to be important for the structures with N=1%, from time‐resolved PL measurements. | Smart windows with controllable visible and near-infrared light transmittance can significantly improve the building’s energy efficiency and inhabitant comfort. However, most of the current smart window technology cannot achieve the target of ideal solar control. Herein, we present a novel all-solution-processed hybrid micronano composite smart material that have four optical states to separately modulate the visible and NIR light transmittance through voltage and temperature, respectively. This dual-band optical modulation was achieved by constructing a phase-separated polymer framework, which contains the microsized liquid crystals domains with a negative dielectric constant and tungsten-doped vanadium dioxide (W-VO2) nanocrystals (NCs). The film with 2.5 wt % W-VO2 NCs exhibits transparency at normal condition, and the passage of visible light can be reversibly and actively regulated between 60.8% and 1.3% by external applied voltage. Also, the transmittance of NIR light can be reversibly and passively... | eng_Latn | 7,901 |
Bound state in the continuum in the one-dimensional photonic crystal slab | In this work we developed a design of one-dimensional Si/SiO2 photonic crystal slab supporting so called optical bound states in the continuum - infinitely high-Q optical states with energies lying above the light line of the surrounding space. Such high-Q states are very perspective for many potential applications ranging from on-chip photonics and optical communications to biological sensing and photovoltaics. | 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 | 7,902 |
Upper pole of a duplex kidney mimicking adrenal incidentaloma in 18F-fluoro-2-deoxy-D-glucose positron emission tomography: a pitfall in diagnosis | 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) has proved to be valuable in the diagnosis and management of a variety of malignancies, but is still limited in providing detailed anatomical information. According to the literature, an adrenal incidentaloma with high FDG uptake usually indicates malignancy and requires further investigation. However, accurate localization of the adrenal gland in FDG-PET is difficult without the presence of surrounding well-visualized organs, such as the kidney or liver. If these organs have a congenital anomaly or are altered due to a previous operation, misdiagnosis can occur. We present a case with right partial duplex kidney accompanied by abnormal urine retention in the upper pole, which was misinterpreted as an adrenal incidentaloma in FDG-PET. A subsequent CT scan revealed a normal right adrenal gland, but a right partial duplex kidney. Fusion of the PET and CT images showed that the right adrenal lesion seen in the PET image corresponded to the u... | This article is dealing with simulation of deployment of EDFA optical amplifier in different positions (post- amplifier or booster, in line and pre-amplifier) used for GPON downstream, which depend essentially on the opt-geometric parameters (ions erbium density and length of the fiber doped erbium) and the effect of those parameters to optimize the performance for extending the reach up to 60 km of and with 1:128 split ratio of the GPON. The performance of this system has been evaluated in terms of the quality factor, eye diagram and the minimum of BER with various simulations by sweeping fiber length and input signal power. It has been found that, the pre-amplification was performed and found to be superior with good results to inline and post amplificationn methods. | eng_Latn | 7,903 |
Passive integrator for ILDAS project | The analogue integration of a signal is useful in many areas of physics and electrical engineering. We describe a temperature stable passive integrator capable to measure the signal in the frequency range up to 170 MHz. | We report carrier lifetime reduction in GaInAs/InP multiple quantum wells from 3Ons to 95ps using mesas with ion implantation of the sidewalls.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | eng_Latn | 7,904 |
Atmospheric oxidation of chlorinated ethylenes | A process for producing aromatic polyamides having improved nonflammability characteristics in which a polyamide substrate is contacted with a gaseous medium comprising a minor amount of a haloolefinic material and an inert diluent in the presence of light having sufficient energy to effect chemical addition of the haloolefin to said polyamide substrate. | 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. | eng_Latn | 7,905 |
PAN‐DA: An integrated distributed data acquisition sytem | PAN‐DA is the overall name given to the new generation data acquisition system being developed for experiments at Fermilab by the Data Acquisition Support Department. This system has been designed to allow easy support for new specific modules and processors, flexible migration to new front end readout controllers and event builders, new event filter processor boards and data acquisition buses, and integration of heterogeneous backend online computer systems for data acquisition control and monitoring. | 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 | 7,906 |
Progress in Quenching Circuits for Single Photon Avalanche Diodes | An ever wider variety of applications employ Single Photon Avalanche Diodes (SPADs) for the detection of faint optical signals. SPADs are p-n junction biased above the breakdown voltage and operate in Geiger-mode: each electron-hole pair can trigger an avalanche multiplication process that causes the current to swiftly rise to its final value. Additional quenching electronics is necessary for a SPAD proper working. The additional electronics characteristics directly affect the system's obtainable performances. Different quenching circuits affect the detector performances in different ways. In the last 15 years there has been considerable development in the integration of the quenching circuitry directly with the detector, thus leading to improved performances. This paper reviews the state of the art of this evolution, examining and comparing different classes of quenching circuits and explaining their mode of operations, their advantages and disadvantages. | We introduce in this paper a carrier phase detector suited to transmissions at very low signal to noise ratio. Based on the soft decoding of parity check equations, the synchronization scheme proposed here for a QPSK modulation outperforms a classical decision directed algorithm over a Gaussian channel, and is notably well adapted to satellite applications. | eng_Latn | 7,907 |
Near unity input displacement factor for current source PWM drives | A simple control scheme for near unity input displacement factor (IDF) operation of the three phase current source type PWM rectifier is proposed. The rectifier is operated by a conventional selective harmonic elimination pattern with 420 Hz switching frequency, which is feasible for GTO switches used in high power applications. The article includes a description of the proposed control scheme, IDF compensation limitations based on power circuit components, and simulation results for steady state and transient conditions. We also investigate the IDF values for PWM CSRs with various control strategies supplying CSI based AC drives with different types of industrial loads. Based on the results presented, a power factor correction scheme may not be necessary for a CSR-CSI AC drive supplying a particular type of load. Experimental results on a 10 kVA GTO PWM rectifier are included to confirm the feasibility of the proposed scheme for high power applications. | This work shows that the performance of optical receivers designed in silicon deep-sub-micron CMOS technologies competes successfully with more expensive SiGe-BiCMOS receivers in data rate and sensitivity. In burst-mode applications of passive optical networks, the transimpedance of the low-noise amplifier has to be switched very fast requiring, the exclusion of oscillations. To meet the burst-mode requirements, our design for 2.5 G bit/s in 120 nm CMOS offers a fast switching of the transimpedance within 3 ns and proves a low-distortion signal detection. Copyright © 2007 John Wiley & Sons, Ltd. | eng_Latn | 7,908 |
Engineering Efficient, Broadband Upconversion in Core/Rod/Emitter Semiconductor Nanostructures | We characterize upconversion (UC) photoluminescence (PL) in semiconductor quantum dot/rod/emitter nanostructures using one- and two-color cw excitation. We engineer improvements in UC quantum efficiency to 3% of the PL emission efficiency. | In this paper, the structure characteristics of a transmitting device with stepped fit for high speed motorized spindles, and a detailed process of stress analysis to the shrink fitted joint in finite element analysis method is introduced. The reasonability of the structure design and reliability of the surplus joint are verified by analysis results. | eng_Latn | 7,909 |
Some studies of avalanche photodiode readout of fast scintillators | Recently large area avalanche photodiodes with high performance, narrow operation tolerances and high reliability became available. We report on some tests of their performance for the readout of fast scintillators. > | We propose an alternative method for the detection of SPDC photons and their temporal correlations. all this doing mainly by photon counters,a BBO crystal type II, a PBS and taking counts on fundamental points (Control points). | eng_Latn | 7,910 |
Submillimeter wave generation by nonstationary mixing | Three-wave interaction of picosecond pulses was investigated for difference frequency generation with AgGaSe2 and AgGa 1-x In x Se 2 crystals. Group velocities and radiation absorption were taken into account during spectral analysis realization. Calculations were executed for CO 2 laser parameters: 100-5 ps, 15-150 GW/cm 2 . Spectral characteristics and pulse power versus crystal length are represented for difference wavelength 800.5 μm. | We show <-50 dB AM-to-PM conversion over a wide photocurrent range in MUTC photodiodes. By controlling the AM-to-PM coefficient minimum, we generate 15 dBm microwave power with 60 dB AM rejection onto the microwave phase. | eng_Latn | 7,911 |
Voltage controlled dual-wavelength ZnO/Au/MgZnO UV photodetectors | Abstract In this work, dual-wavelength UV photodetectors were successfully constructed by growing ZnO and MgZnO layers on SiO 2 substrates with ZnO/Au/MgZnO structure. The photodetectors exhibited high performance and the influence of different thickness of MgZnO layers was investigated. Moreover, simply by adjusting the applied voltage on the devices, the ratio of the two response peaks (caused by MgZnO and ZnO layers) changed therewith. The detecting properties may originate from the two layers having different increasing rates where the existence of Schottky junctions plays an important role. The photodetectors are meaningful for fabricating dual-wavelength optoelectronic devices for practical applications. | We have already proposed two types of integrated micro MO heads for Mini Disc and reported on their characteristics [1],[2],[3]. These heads are made by forming optical elements such as holograms and beam splitters in multiple parallel glass plates. The type 1 head is made by laminating a 44 μm thick half-wave plate as an azimuth rotator[1],[2]. On the other hand, the type 2 head includes, instead of a half-wave plate, a polarization beam splitter which has a sloping incident plane making an angle of 45 deg. to the incident plane of polarization [3]. In this paper, we report mainly on the detailed structure of the integrated MO head developed for the Mini Disc, the characteristics of each optical thin film for the finite conjugate optical system used in this device, and the simulation results for a number of optical characteristics. | eng_Latn | 7,912 |
Adaptive Equalization for SQPSK and SQPR Over Frequency Selective Microwave LOS Channels | This paper compares the effectiveness of linear and decision feedback equalizers in counteracting the effect of frequency-selective distortion in microwave relay links. A quadratic frequency-selective model of the channel is employed and particular attention is given to channels with a null in the passband. Both staggered QPSK and QPR modems are studied. Performance is studied for error probability and mean squared error. The general conclusion is reached that a decision feedback equalizer is required for robust performance. | 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 | 7,913 |
Passive remote sensing technology for mapping bull kelp (Nereocystis luetkeana): A review of techniques and regional case study | Abstract The distribution and abundance of the canopy-forming kelp Nereocystis luetkeana is of increasing concern for environmental management and conservation in coastal regions due to its importance as a foundation species. Mapping kelp forests aids in understanding their health, productivity, and response to environmental conditions. Remote sensing using satellites is an increasingly accessible tool for mapping nearshore habitats allowing for applications such as long-term monitoring and large- and small-scale surveys. This paper provides a review of passive optical remote sensing techniques for detection and mapping of floating macro-algae, and adapts these techniques for detecting Nereocystis luetkeana , demonstrating their application through a comprehensive case study, from imagery acquisition to map validation. This review with associated case study communicates to non-remote sensing experts a road map to use remote sensing technology for mapping kelp habitats. | For many years it has been assumed that nonradiative recombination plays a dominant role in determining the high temperature performance of long wavelength laser diodes. We show that this view is inconsistent with the measured temperature dependence of spontaneous emission from light emitting diodes. We conclude that net gain primarily determines the temperature sensitivity of threshold in long wavelength semiconductor lasers. | eng_Latn | 7,914 |
Interference phenomena in time-resolved stimulated Raman measurements | Abstract We demonstrate that in time-resolved stimulated Raman measurements (TSRS) at specific values of the mistuning of the driving frequency with respect to the eigen frequency of the Raman mode a spectacular dip in the time response of the oscillator appears. We explain this phenomenon as an interference effect between the driving force and the excited mode. We found both qualitative and quantitative agreement between our TSRS measurements and a computer model that is based on a simple extension of the damped harmonic oscillator. | Periodic arrays of microresonators coupled to channel waveguides, and Bragg stacks of quantum wells, are two drastically different physical systems that exhibit the same dispersion relation. Similarities and differences in their optical properties are presented. | eng_Latn | 7,915 |
Single-longitudinal-mode semiconductor laser with digital and mode-hop-free fine-tuning mechanisms. | We report a novel external cavity laser diode (lambda= 1.5 mum). An intra-cavity liquid crystal pixel mirror allows digitally tuning of the laser wavelength to more than 40 wavelength channels of 100 GHz spacing according to the International Telecommunication Union (ITU) grid. Laser wavelength can further be fine-tuned by varying the driving voltages applied to an intra-cavity planar nematic liquid crystal phase plate. With a cell 52.3 mum in thickness, the output frequency can be continuously tuned over 1.89 GHz. The root-mean-square voltage required for driving the phase plate was from 1.00 to 4.56 volts. | Summary Diffractive optical element (DOE) is a promising technique to realize beam smoothing. To calculate the true performance of the DOE for beam smoothing, the spatial-frequency spectrum method has been used to re-define the performance parameters of the DOE for beam smoothing. In this paper, the spatial-frequency spectrum method is used to basically determine the performance limitation of the DOE for beam smoothing. Considering the low-pass filtering effect will be induced by physical process in the practical applications, the DOE is designed with the low-pass filtering effect in the optimization. Furthermore, the performance realized by utilizing the DOE and the time average technique is theoretically analyzed with the spatial frequency spectrum method. | eng_Latn | 7,916 |
compact simulation model for an optical modulator | The invention relates to a simulation model for an optical modulator, the modulator comprising an optical phase shifter in a semiconductor material, configured to be disposed between two sections of an optical waveguide; and a PN or PIN junction formed in the phase shifter in a plane parallel to the axis of the waveguide. The modulator comprises a diode model model (30) characterizing the electrical behavior of the junction. The change in the overall refractive index (An) of the phase shifter is expressed in proportion to the quantity of charges (Nd, Ni) present in the junction area, determined from the diode model, raised to a power, the coefficient of proportionality and the power being empirical values depending on the semiconductor material and the wavelength. | The present paper presents a new contribution to the design of output regulators for a class of nonlinear systems characterized by a possibly unstable zero dynamics. It is shown how the problem in question is handled by addressing a stabilization problem for a suitably defined reduced auxiliary plant. | eng_Latn | 7,917 |
Research progress on flashlamp-pumped solid-state heat capacity slab laser | Progress of a flashlamp-pumped solid-state heat capacity slab laser is presented.Based on large-aperture Nd:YAG slabs,a Brewster-angle and V-shaped active mirror configuration of laser was designed respectively.The passive loss and gain performances were measured experimentally for these two kinds of lasers.An output of 47 J in pulsed operation,and average power about 1kW was obtained experimentally.Based on power scaling experiments,a high–average-power approach with such active-mirror configuration was also discussed. | The article describe operating principle of the single-particle microbeam device,we implanted the SAM and RAM of embryos with a 2.0 MeV of energy and 25 μm of diameter proton microbeam at the fluence of 6×106ions.The embryos' root patterning parameters was observed in detail,such as the development of primary root and the formation of lateral root.The results indicated that some contributions of vacuum treatment might be involved in the biological effects,ion-beam bombardment and the interactions might be existed between each other.The results showed that auxin signal transduction might be relevant. | eng_Latn | 7,918 |
Polarisation-insensitive wavelength conversion and phase conjugation using bi-directional forward four-wave mixing in a lasing DFB-LD | A polarisation-insensitive wavelength converter is proposed using bi-directional nondegenerate forward four-wave mixing in a lasing DFB-LD in which the lasing beams are used as pump waves. The converter suppresses the polarisation sensitivity of conversion efficiency to within 0.4 dB, and demonstrates a 10 Gbit/s wavelength conversion and optical phase conjugation. | 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‰. | eng_Latn | 7,919 |
Ion-exchanged Er/Yb waveguide laser at 1.5 µm pumped by laser diode | A diode-pumped planar Er/Yb waveguide laser is demonstrated. The device was fabricated by thallium exchange in a phosphorus-free silicate glass. Lasing was achieved at 1544 nm with a threshold of 5 mW and a slope efficiency of 2%. The low threshold indicates the absence of the severe backtransfer effects previously reported in Er/Yb bulk laser silicate glasses. | Long pulse operation has an important impact on the design and utilization of a neutral beam injection system. This paper, first describes briefly the injectors designed for ITER FEAT as they are the first to be designed for long pulse operation under conditions approaching those that will be experienced in future machines. The important consequences of long pulse operation on the injector design will be then discussed, and finally some suggestions will be made for future, continuously operating systems. | eng_Latn | 7,920 |
Three-dimensional skin imaging using the combination of reflected confocal and multiphoton microscopy | Reflected confocal microscopy has been widely used in clinical application in dermatology. In recent years, ::: multiphoton microscopy has also emerged as an important minimally invasive bioimaging technique for the skin. In this ::: study, we combine reflected confocal microscopy and multiphoton microscopy for skin imaging. In the epidermis, ::: reflected confocal signals are expected to help in delineating cell borders while multiphoton signals provide cytoplasmic ::: morphologies. In the dermis, second harmonic generation signals provide the morphology of collagen fibers. When ::: three-dimensional images are projected, the detailed distribution of cellular component and extracellular matrix in skin ::: can be obtained. Properly developed, this technique is of great potential for in vivo clinical application. | Conventional microwave transversal filters are hindered by bandwidth limitations and cannot provide long-time delays due to excessive propagation losses. Optical transversal filters lack the means to provide negative weighting coefficients. Therefore, a hybrid transversal filter that utilizes low loss, wide bandwidth optical fibers for the delays and microwave monolithic integrated circuits (MMIC's) for accurate weighting is investigated. Theoretical analysis of the noise performance, bandwidth, and delay fine dispersion of a completed MMIC advanced transversal filter and the novel hybrid transversal filter are presented. > | eng_Latn | 7,921 |
High-Power Double-Clad Fiber Laser | The paper introduces the fundamental principle and main characteristic of high-power double-clad fiber lasers, and then gives the overview of current development of the new fiber lasers. The promising application of double-clad fiber lasers is also prospected. | This paper proposes a novel scheme integrating full-duplex data communication into a wireless power transfer system. The power and data are transmitted on the same inductive link comprised of two coreless coils with taps. Frequency division multiplexing (FDM) technique is applied. The power and data are transmitted by using different frequency carriers. The duplexers are designed to implement full-duplex communication. The circuit model of the system is provided to analyze the power and data transfer performance. The crosstalk interference between power and data carriers is discussed. Finally, a prototype has been built to demonstrate the effectiveness of the proposed system. | dan_Latn | 7,922 |
A stereoselective fluorogenic assay for aldolases: Detection of an anti-selective aldolase catalytic antibody | Abstract Stereoisomeric aldols 6a-d undergo retroaldolization to give 3-oxopropyl umbelliferyl ether 5 and subsequently umbelliferone 4 by β-elimination, leading to a fluorescence increase at λ em = 460 ± 20 nm ( λ ex = 360 ± 20 nm). This fluorogenic assay for aldolases operates in cell culture media and can be used to search for new stereoselective aldolase biocatalysts. Aldolase antibody 38C2 (Aldrich no. 47,995-0) catalyzes stereoselectively the retroaldolization of (S)-anti aldol 6c . | In this paper, we have theoretically studied the dynamical behavior of current modulated semiconductor ring lasers (SRLs). As we vary the amplitude and frequency of the modulation around a fixed bias current, difference dynamical states including periodic, quasi-periodic and chaotic states are found. As in other single mode semiconductor lasers, the modal intensities in an SRL present chaotic behavior for driving frequencies comparable to the relaxation oscillation frequency. In this regime the two counter-propagating modes vary in phase. However, for modulation frequencies significantly lower than the relaxation oscillation frequency, we reveal the existence of chaotic oscillations where the two counter-propagating modes are in anti-phase. | eng_Latn | 7,923 |
A Revised Shear-Lag Analysis of an Energy Model for Fiber-Matrix Debonding | A shear-lag analysis based on energy is used to predict the amount of debonding thatoccurs when a flber fragment breaks into two fragments. The shear-lag analysis repro-duces all features of more sophisticated analyses. A drawback of the shear-lag analysis,however, is that it depends on an unknown parameter which can be expressed in termsof an | Abstract Broadband sum frequency conversion of a slab RF discharge Q-switched CO laser system was performed with two BaGa2GeSe6 crystals resulting in its spectrum lying within 1.7–6.0 μm spectral range. The first BaGa2GeSe6 crystal was located in the CO laser cavity and operated as both CO laser sum frequency (second harmonic) generator and laser output coupler. Another BaGa2GeSe6 crystal was applied for external third harmonic generation, i.e. as sum frequency generator for fundamental CO laser radiation and its sum frequencies obtained within the cavity. Peak powers of fundamental CO laser radiation, its second and third harmonics were up to 4.7 kW, 100 W and 0.5 W, respectively. | eng_Latn | 7,924 |
Communication: High speed optical investigations of a character of boiling-up onset | In this communication, we discuss the phenomenon of attainable superheat of liquid and the peculiarities of its release by spontaneous boiling-up. We have combined the apparatus for superheating, namely, bubble chamber, with a high speed micro-optical method for detailed monitoring of the initial stage of boiling-up. In experiments on the isothermal pressure drop, it was found that the boiling-up onset of n-hexane is accompanied by characteristic step signal. The signal has proved to be typical of the heterogeneous character of boiling-up onset in a whole range of superheating degrees. The performance of the method for investigation of the refractive index and density for superheated liquids as functions of temperature and pressure has been revealed. The experimental error is estimated to be 0.1%. | Optical data transmission applications emerging from the Roadmaps; raising Telecom bandwidth efficiency, the role for PICs; microprocessor IO Bandwidth density and optical interposers; data center power reduction; optical backplanes; on-chip interconnect. | eng_Latn | 7,925 |
Photon-energy dissipation caused by an external electric circuit in "virtual" photoexcitation processes. | We consider generation of an electrical pulse by an optical pulse in the ``virtual excitation'' regime. The electronic system, which is any electro-optic material including a quantum well structure biased by a dc electric field, is assumed to be coupled to an external circuit. It is found that the photon frequency is subject to an extra red shift in addition to the usual self-phase modulation, whereas the photon number is conserved. The Joule energy consumed in the external circuit is supplied only from the extra red shift. | In this paper, a novel 3-dimensional pattern of partial discharge (PD) was set-up based on the theory of wavelet analysis. The PD pattern could reflect the discharge characteristic. The parameters which characterize the PD were the frequency, the time and the energy. The fractal theory was adopted for the feature extraction and classification. The experiments have been carried out to validate the method with three kinds of artificial PD models. The results indicate that the proposed methodology has the recognizing and classifying ability for the PD types. | eng_Latn | 7,926 |
Nonvolatile phase change memory nanocell fabrication by femtosecond laser writing assisted with near-field optical microscopy | The phase change memory cells were developed by using a combination system of a femtosecond laser with near-field scanning optical microscopy. The memory cells with feature size varying from 800nm down to 90nm were achieved. The cell functional performances were tested, and the scalability of the programming current as a function of the memory cell features was investigated. The optical near-field distance which is one of the critical factors to achieve high resolution nanostructures was studied experimentally with the consideration of the whole fabrication process for functional devices. The Bethe-Bouwkamp model was employed to study the effects of the optical near-field distance to the nanostructure geometry. The programming current of 0.8mA was observed for the memory nanocell at a feature size of 90nm. | Adopting a nonlinear dynamical system analysis point of view, we discuss the design of a low-complexity CMOS electronic circuit implementing a Physically Unclonable Function core module based on a two-neurons Cellular Neural Network. The study follows a theoretical approach investigating the circuit topology, aiming at proposing a methodological engineering approach for the design of this class of systems. | eng_Latn | 7,927 |
Quantitative autofluorescence in retinal disease | Fundus autofluorescence (AF) is a retinal imaging modality based on the emission of light by the retina after stimulation at specific wavelengths, either 488 nm (blue autofluorescence, BAF) or 787 nm (near-infrared autofluorescence IRAF). | We demonstrate all-optical bistable memory operation with 1.3 Q-InGaAsP photonic crystal nanocavities based on refractive index modulation caused by carrier-induced nonlinearity. The minimum bias power for bistability is extremely low at a few tens of muW and the operating energy required for switching is only 30 fJ. | eng_Latn | 7,928 |
Faster Switching with Semiconductor Optical Amplifiers | 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. | Multilevel Conversion systems have certain advantages that can be applied in renewable energy systems. To verify that advantages we are developing a re-configurable 1 kW prototype. Among the experiments that we have considered, a sliding mode control law can force this converter to behave like an AC Current Source. We model our converter like a set of Tibuck converters operating sequentially. Some experimental results are given. | eng_Latn | 7,929 |
Wide range of operating conditions for a 1000 km-2.5 Gb/s transmission with a new WDM optimized design of integrated laser-electroabsorption modulator | A new wavelength-division multiplexed (WDM) optimized design of integrated electroabsorption modulator distributed feedback lasers provides a great tolerance on operating conditions and laser wavelength: 2.5 gbit/s transmission over 1000 km is performed for /spl Delta/I/sub laser/=70 mA, /spl Delta/T/sub chip/=20/spl deg/C, and /spl Delta//spl lambda//sub laser/=10 nm. | We present experimental and theoretical studies of the diffraction by an x-ray lamellar multilayer amplitude grating. The main diffraction properties of such a device are given. Experimental efficiency curves are obtained at 800 eV photon energy using synchrotron radiation. The features observed in these curves are identified and interpreted by means of two theoretical methods. Particular emphasis is given to structures observed for the first time which had been theoretically predicted. | eng_Latn | 7,930 |
Nonlinear effects in femtosecond pulse amplification using chirped fiber gratings | The objective of this paper is to investigate, both theoretically and experimentally, the limits on maximum pulse energy from a fiber-grating-based all-fiber system and to reveal methods for improving and optimizing its overall performance. We have found that for fiber gratings manufactured in a standard single-mode fiber the pulse energy limit is of the order of 20-50 nJ, which is on the same level as from currently available bulk, large-frame femtosecond lasers. This demonstrates the potential of this compact all-fiber design for generating high-power ultrashort pulses. | Nonlocal continuum damage modelung using the gradient enhanced damage model and the phase-field model for brittle fracture. | eng_Latn | 7,931 |
Novel nonlinear nanophotonic phenomena | We present our theoretical and experimental work on one-way waveguides, analogous to quantum-Hall edge states. We also discuss some possible applications, as well as the possibility of breaking time-reversal symmetry using active meta-materials. | In this paper, the application of scanning near-field photon emission microscopy for imaging photon emission sites is demonstrated. Photon emissions generated by a Fin-FET test structure with one metallization layer are imaged with spatial resolution of 50 nm using scattering dialectic probe. The potential applications and limitations of the technique are discussed. | eng_Latn | 7,932 |
Noise characteristics and linewidth of a semiconductor laser with phase-locking feedback | An improved model of an optical phase-locked loop (OPLL) is presented. Based on this model and rate equations of an external cavity semiconductor laser, the effects of OPLL feedback on the FM noise and the AM noise of the external cavity semiconductor laser are discussed. A new linewidth formula of the local laser is derived.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | Two-dimensional images of the distribution of values of acoustic attenuation (A) and velocity (V) in coronal planes of excised human female breasts were obtained using computer assisted tomography (CAT) techniques. Projection profiles of amplitude attenuation and of propagation delay of acoustic pulses were obtained by rectilinear transverse scanning of the tissue under study. Over 200 equispaced pulses were obtained along a 15 cm scan for each of about 35 angles of view separated by 5.4°. Focusing acoustic lenses were used to insonify as small a volume as possible in order to minimize the probability of receiving pulses from multiple pathways. The received pulses were digitized at one 8-bit sample every 10 nanoseconds for up to 1,024 samples. Edge detection algorithms were used to determine the arrival time of the pulse within the digitized signal. The amplitude of the arriving pulse was determined by measuring the peak or the area of the earliest arriving pulse. | eng_Latn | 7,933 |
Low-energy ultrafast fiber soliton logic gates. | We have reduced the switching energy for an all-optical soliton dragging nor gate to 5.8 pJ by using a two-fiber configuration and optimizing the fiber and laser parameters. The cascadable nor gate has a fanout of six, restores both the logic level and timing, and can operate at bit rates of up to 0.2 THz. In addition, we show that soliton dragging can be represented as a generalized exclusive-or module with high functionality. Two such modules can be interconnected as nor and and gates or broadcast and routing switches. | 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 | 7,934 |
Measurement of direct frequency modulation characteristics of DFB-LD by delayed self-homodyne technique | The direct frequency modulation characteristics of a DFB-LD can be simply measured by means of a delayed selfhomodyne method using a single-mode fibre delay line and a single-mode fibre coupler. This measuring method has the features of simple set-up and high resolution when narrow-linewidth optical sources are used, compared to the conventional interferometric methods. Direct frequency modulation characteristics of a DFB-LD in the 1.55 ?m region are measured, and the results obtained agree well with those by a Fabry-Perot interferometer. | This invention discloses a method for automatically identifying protection intervals and terminals including: obtaining time domain pulse response of OFDM symbols based on the PN series, estimating the length of OFDM data block roughly based on the peak position of the time domain pulse response, estimating the protection interval length roughly based on the OFDM length and getting the accurate protection interval length based on the peak position in the roughly estimated protection interval, further correcting the length of the OFDM data block and determining the OFDM system transmission mode based on data block length. | eng_Latn | 7,935 |
[Tympanosclerosis of the tympanic membrane]. | The structure of the tympanosclerotic plaques of the tympanic membrane was examined by using the scanning electron microscope. Studies were carried out on specimens of the tympanosclerotic plaques obtained during surgery in 15 patients for chronic middle ear inflammation. It was found that tympanosclerotic plaques contained fibrous fibers of different densities, distribution and calcification, and without cellular elements. The authors recognized two types of plaques, with moderate and severe degree of calcifications. The results showed that the role of a degenerative process was dominant in the pathogenesis of tympanosclerosis. | In this paper, we investigate the performance of the Sub-carrier Multiplexed-Free Space Optics (SCM-FSO) for transmitting Code Division Multiple Access (CDMA) signals in terms of Carrier-to-Noise-plus-Interference Ratio (CNIR) and Bit Error Rate (BER), under Gamma-Gamma turbulent FSO channel. We propose an analytical model for optimization of the SCM-FSO link and a closed-form BER expression taking into account the nonlinear effects of the SCM optical link as well as the strong atmospheric turbulence of the FSO channel. We emphasize how the choice of optimal optical modulation index (OMI) can increase the received CNIR and also its dependency on the attenuation of the FSO channel. We then discuss the effect of atmospheric turbulence on the received BER. It is shown that, for a high quality CDMA signals reception over the SCM-FSO system, the link has to be engineered to perform optimally in terms of received optical power, number of carriers and OMI. | eng_Latn | 7,936 |
Bidirectional optical transceiver with automatically directional controlling function | A bidirectional optical transceiver with an automatically directional controlling function is designed and implemented in a 0.18 μm CMOS technology. A novel transmission envelope detector functions as the directional controlling block to generate the controlling signals according to the received optical signal. The bidirectional optical transceiver achieves a 3-dB bandwidth of 4.4 GHz and 4 GHz in transmitter (Tx) and receiver (Rx) modes respectively, while the disabled outputs for the Tx or Rx modes are isolated with −19 dB and −17 dB, respectively, from the enabled inputs. | 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 | 7,937 |
Broad tuning of whispering-gallery modes in silicon microdisks. | Silicon microdisks with dynamically-tunable resonance spectra are achieved with nanoscale, in-plane silicon electrical contacts in a single lithographic step. Electrical current is passed through the devices to enable thermal tuning via joule heating. A 14nm wavelength shift is demonstrated with 1.6mW power consumption in devices with >20nm free spectral ranges and quality factors exceeding 20,000. Spectral shifts equal to a full width at half maximum can be achieved with approximately 10microW tuning power for a mode with quality factor of 20,000. | This paper discusses some potential approaches to developing next-generation radar technologies via the development of ::: smart hardware subsystems that have the intrinsic capability to compensate for channel warping and propagation ::: distortions. Discussions with regard to typical categories of propagation distortions are provided along with a series of ::: sample scenarios that can provide challenging conditions for radar remote sensing applications. Observations of this set ::: of sample scenarios allows for the exploration of potential approaches to developing state-of-the art digital, RF, and ::: RF/Photonic technologies with intrinsic smart compensation capabilities that will enable the development of highresolution ::: radars that can operate at longer ranges while maintaining compact size and weight requirements. | eng_Latn | 7,938 |
The principle of logic pulse width modulation(LPWM) converter | DC-AC converter,single-phase bridge DC-AC converter and three-phase bridge converter were combined together for proposing the method of LPWM.Then the verification of LPWM control method was carried out by simulating LVPWM and the experiment of orthogonal two-phase mixing battery power based on the LPWM control method. | Summary A low frequency noise analysing system is set up with a multi-channel detector. The multi-channel detector includes a PCD Image Sensor which has 256 sensing elements. Light output of a laser diode is divided into various wavelengths. The light spectral intensities are measured at various wavelengths. | eng_Latn | 7,939 |
Solid breast neoplasms: Differential diagnosis with pulsed Doppler ultrasound | In this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow. A positive Doppler signal, i.e., a Doppler shift frequency of more than 1 kHz using a 5 MHz insonating frequency, was found in 34 of 57 patients with a carcinoma, and also in three patients with a benign condition. These results indicate that negative findings with pulsed Doppler ultrasound cannot be used to exclude malignancy. However, a frequency shift of more than 1 kHz indicates a high probability for malignancy. In our study a high frequency shift was not related to tumor size. We also evaluated the correlation between a high frequency shift and axillary nodal metastasis. According to our results there is a very low chance of axillary metastasis when no high frequency shifts are found. | 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. | eng_Latn | 7,940 |
Development of SCAR Marker Linked to Cucumber Anthracnose Resistance-related Gene from an AFLP Marker | The co-dominant AFLP marker of anthracnose resistance-related gene of cucumber was con- verted into co-dominant SCAR marker successfully.After sequencing of the AFLP marker fragment,two pairs of primers were designed according to the nucleotide sequence.PCR results from cucumber genomic DNA showed the two primer pairs (1 and 2) could amplify two band types with the size of 131 bp/125 bp and 178 bp/172 bp,respectively.Both 131 bp band and 178 bp band were the character band of anthracnose resist- ance phenotype.These SCAR markers were designated as SCEM131/125 and SCEM178/172.Anthracnose resistance of F_2 and some resistant and susceptible cucumber lines were tested by SCAR markers,and the re- suits indicated that the resistance tested was consisitent with their field performance by 97.27%,which further confirmed the feasibility of the SCAR markers in MAS for cucumber anthracnose. | We present an analytical derivation of the distributed model from the experimentally well confirmed lumped approach for the description of light propagation in mode-locked fiber lasers operating in the scalar regime where the dynamics is mainly governed by the propagation of a single field component. As a limiting case of the distributed model we identify the complex cubic-quintic Ginzburg–Landau equation (CQGLE). One important result consists of deriving explicit relations between the coefficients of the distributed models to the realistic laser parameters. We numerically demonstrate that the results obtained by using the general distributed model are in very good agreement with those of the lumped model, whereas results of the CQGLE can significantly deviate for a certain range of parameters. Moreover, we demonstrate that the validity of the CQGLE approach strongly depends on the operation regime of the saturable absorber. | eng_Latn | 7,941 |
Single phase switch mode rectifiers | Six new circuits of single-phase boost type switch mode rectifiers (SMRs) are presented in this paper. These SMRs can use any of the constant or variable switching frequency control techniques for the input supply current waveshaping. Experimental results for unity power factor operation are provided for three of these SMRs. | We have developed a detection technique to reduce the effect of DMD without sacrificing the advantages, such as alignment tolerance and ease of manufacturing, related to the use of multimode fiber. Our method is a simple implementation of spatially resolved equalization (SRE) that doubles the bandwidth of MMF links. Using an overfilled launch condition, we exploit the spatial diversity of the optical signal emitted from the MMF. We use a SRE detector, an InGaAs metal-semiconductor-metal (MSM) device placed 400 /spl mu/m from the fiber end. | fra_Latn | 7,942 |
High-resolution coherent reflector location with multi-frequency active virtual arrays | We present a method to improve high-resolution imaging of coherent point reflectors with transmit/receive arrays. The data obtained from the array can be rearranged into a virtual data matrix to resolve additional reflectors. The problem with using a virtual array is that it may not necessarily be able to resolve coherent reflectors due to a rank deficiency in the source correlation matrix.We use the idea of array interpolation to allow for more coherent reflectors to be resolved than conventional techniques by averaging over multiple frequencies. Averaging over multiple frequencies allows for an effective full-rank source correlation matrix. | 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 | 7,943 |
Pulsed electrical operation of 1.5-μm vertical-cavity surface-emitting lasers | Vertical cavity surface emitting lasers operating in the 1.3- and 1.5-/spl mu/m wavelength ranges are highly attractive for telecommunications applications. However, they are far less well-developed than devices operating at shorter wavelengths. Pulsed electrically-injected lasing at 1.5 /spl mu/m, at temperatures up to 240 K, is demonstrated in a vertical-cavity surface-emitting laser with one epitaxial and one dielectric reflector. This is an encouraging result in the development of practical sources for optical fiber communications systems. > | This study compared ultrasonic and laser measurements of citrus canopy volume with manual measurement ::: methods. Fifteen trees with different canopy heights and volumes were used. Manual and ultrasonic measurements provided ::: dimensions for computing the canopy volume whereas laser measurements gave information that could be used to compute ::: a ‘laser canopy volume index.’ Ultrasonic and laser methods agreed with manual methods (R 2 > 0.85, RMSE < 2.15 m 3 ). Laser ::: showed better prediction of canopy volume than the ultrasonic system because of the higher resolution. Ultrasonic or laser ::: sensors can be used for automatic mapping and quantification of the canopy volumes of citrus trees. | eng_Latn | 7,944 |
Laminate, method for producing laminate, light guide body for light source devices, and light source device | A laminate which comprises a core layer, a first cladding layer, a second cladding layer and a light reflecting layer, and wherein the light reflecting layer, the second cladding layer, the core layer and the first cladding layer are sequentially laminated. The refractive index of the first cladding layer and the refractive index of the second cladding layer are lower than the refractive index of the core layer, and the light reflecting layer has a thickness of 50 μm or more. | We report on ultrafast control of the charge state of a single InGaAs quantum dot in a charge-tunable p-i-n diode structure. Focused ion beam etching is employed to decrease the capacitance of the device to enable radio frequency operation. A time-resolved photoluminescence technique is demonstrated that allows monitoring the charge state with a time-resolution which is limited only by the radiative lifetime of the charged and neutral exciton, respectively. Experimental data show that the charge state can be manipulated on time scales shorter than the radiative lifetime of approximately 1.4 ns. | eng_Latn | 7,945 |
Focusing limits of intense ultrafast laser pulses in a high pressure gas : road to new spectroscopic source | As a result of focusing ultrafast Ti:Sapphire laser pulses in a gas, a plasma column is created. Its density does not exceed some limiting value as a result of the defocusing by the electrons resulting from multiphoton ionization and the involvement of high order nonlinearities. The spectrum of the radiation from the excited species in the column has little contribution from the plasma continuum and the line broadening is less than that of the spectra radiated from a plasma generated by a long laser pulse. Thus, the spectroscopic source obtained using short laser pulses is an excellent source for spectroscopy. | We present a detailed study of the optical trapping and manipulation of nanoparticles with complex permittivity using an apertureless near-field probe. We use a three-dimensional, self-consistent description of the electromagnetic scattering processes that accounts for retardation and the intricate many-body interaction between the substrate, the particle, and the probe. We analyze the influence of absorption on the optical force. For metals we describe how the optical force spectrum is influenced by the optical response of the metal, and in particular by plasmon resonances. We find that the optical force spectrum can provide an intrinsic signature of the particle composition which can be used to achieve a material-selective trapping and nanomanipulation. | eng_Latn | 7,946 |
Design, assembly, and testing of an objective lens for a free-space photonic switching system | The design, assembly, and testing details of an objective lens used to image an array of 4096 beams are discussed. The main characteristics of the lens are a 15-mm focal length, a speed of f/1.5, diffraction-limited quality, telecentricity, f-sin(θ) mapping, an external stop, and a simplicity of fabrication. | The present invention may be conveyed without increasing the volume of the vacuum chamber via preparatory larger substrate preparatory vacuum chamber. In the interior of the load lock chamber (20) is connected to the vacuum processing chamber is provided: a base plate with a laminate (71) and a plurality of slide plates (72-74), the multi-stage conveyance operation slidably substrate transfer mechanism (70); a support pin (85) and the center of the cushion plate (81, 82) having a peripheral portion of the support substrate and the support substrate G G substrate transfer mechanism (80). In this way, the transfer operation of the substrate G between the atmosphere side of the conveying mechanism (50) provided on the atmospheric side of the transfer arm (51) and the substrate transport mechanism (70) and bending of the substrate may not G. | eng_Latn | 7,947 |
[The L-arginine/nitric oxide metabolic pathway. Its physiopathology and clinical implications]. | The L-arginine/nitric oxide (NO) pathway plays a key role in a number of biological processes within most organs and systems. Increasing attention has been addressed to its involvement in the pathogenesis of various human diseases. In this review we examine the enzymology of different NO-synthase isoforms, the major NO detection techniques as well as the possible clinical and pharmacological implications of this new metabolic pathway. | Based on the small gain approximation in the unsaturated regime in this paper we present the derivation and the evaluation of the spectral optical gain, spectral noise figure and spectral quality factor on single and double pass configuration Er3+-doped LiNbO3 waveguide amplifier pumped near 1484 nm. The simulations show the evolution of the above mentioned parameters under various pumping regimes. In the present work we demonstrated that high gains and low noise figures are achievable in high pump regimes and double pass configuration. The obtained results can be used to theoretically model the optical amplification around 1500 nm in Er3+-doped LiNbO3 waveguides are function of various parameters. | eng_Latn | 7,948 |
Sputter ion pump element pumping speed measurement with the help of a Monte Carlo code | As part of the design of the vacuum system of a new Synchrotron Light Source for Brazil – SIRIUS, the Vacuum Group from the Brazilian Synchrotron Light Laboratory (LNLS) proposed the pumping speed study of a sputter ion pump element assembled inside the vacuum chamber. This configuration aims to reduce components attached to the chamber enabling an easier alignment procedure and a conductance enhancement to pumped gases. The study was carried out by experimental measurements and numerical simulations using Monte Carlo method. ::: The measurements and Monte Carlo calculations results presented a good agreement, with errors less than 10%. Further, inserting the element in the vacuum chamber enhanced maximum pumping speed when compared with the manufacturer’s data, due to the conductance’s increase for gases. | 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). | eng_Latn | 7,949 |
Photon echo in the ensemble of semiconductor quantum dots spread on a glass substrate | Simple procedure to prepare samples containing semiconductor quantum dots was developed. Test photon echo measurements in the ensemble of quantum dots spread on a glass substrate were performed to study optical dephasing processes. | With the development of all-optic network, the hotspot of the research is moving from the backbone network to the metropolitan network, and then to the access network. Much attention has been paid on reducing the cost in these networks. One approach is to adopt Ethernet passive optical network (EPON) architectures in an access network. In this paper a solution of EPON of Broadcasting/WDMA architecture is presented, which is based on several low-cost DWDM devices developed newly by authors, including the precise-wavelength DWDM-LD, DWDM demultipler with interleaver, DWDM receiver array, and dual-window broad-band coupler. | eng_Latn | 7,950 |
OPTICALLY DIGITAL COMMUNICATION AND PROCESSING AT THE QUANTUM LIMIT | 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. | RECEIVING STATION FOR REDUCING A SINGLE CONTROL DEVICE AUTOMATIC TO TREAT DIFFERENT TELEVISION CHANNELS. SHE HAS A PLATINUM CAG UNIQUE IN WHICH THERE IS A LOCAL OSCILLATOR CONTROL VOLTAGE FREQUENCY VARIANT cyclically BASED ON ANALYSIS OF LEVEL OF CARRIER APPLICATION:.. TELEDISTRIBUTION | yue_Hant | 7,951 |
Optical Behaviour of Electroluminescent Devices | In an optical multilayer thin film system, interference effects play an important role for the outcoupling of light due to the different refractive indices and thicknesses of the involved layers. A theoretical model has been investigated with the ability to calculate the outcoupled intensity of light for various wavelengths and viewing angles. ZnS:TbF3 ac-TFEL devices have been prepared to verify the model and to check the applicability of the theory to electroluminescent devices. Experimental and calculated wavelength and viewing angle dependent intensity data show good agreement. The outcoupling efficiency ηopt of a TFEL device can be increased up to 25% compared with the value given by the well known formula of the simple theory /1/. | 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 | 7,952 |
Spontaneous transverse pattern formation in a nonlinear optical medium with feedback mirror | Abstract Spontaneous 2-D transverse pattern formation in a nonlinear optical medium with simple feedback mirror has been deduced by using nonlinear wave equation based on slowly varying amplitude approximation. The physical mechanism and the thresholds conditions of these effects have been discussed. | We recently developed a novel promoter assay system using a retroviral vector (pIP200 series). Transcription from the internal promoter, which had been inserted for the promoter assay, was shown to be interfered with by transcription from the upstream long terminal repeat (LTR). Here we report a new high-titer 'self-inactivating' vector, in which transcription interference was virtually eliminated. This new vector was constructed by introducing only a very minor mutation into the 'TATA box' in the 3'-LTR. This mutation was successfully transferred to the 5'-LTR after reverse transcription, yielding a provirus incapable of transcribing viral RNA. The viral titer was not reduced by the mutation, permitting general application of this virus. | eng_Latn | 7,953 |
Terahertz emission in organic crystals pumped by conventional laser wavelength | Intense Terahertz radiation in organic crystals is typically generated by optical rectification of short wavelength infrared femtosecond lasers between 1.3 and 1.5 μm. In this wavelength range high energy ultrashort pump sources are hardly available. Here we present results on powerful THz generation by using DAST and DSTMS pumped directly by the widely used and well-established Ti:sapphire laser technology, emitting at 0.8 μm. This approach enables straightforward THz generation by optical rectification. We present systematic studies on ::: nIR-to-THz conversion efficiency, damage threshold, and on the emitted THz spectrum and field strength. | The peculiarities of thermooptical sound generation in gyrotropic 2-layered piezoelectric samples was studied. The resonance frequencies of the layered structure was determined. It was established, that the multibeam interference of light waves within layers essentially change the mechanism of PA signal formation. | eng_Latn | 7,954 |
The Raman spectra of Ca(OH)2 and Ca(OD)2 | Abstract The polarized Raman spectra of Ca (OH) 2 and Ca (OD) 2 have been obtained using an argon ion laser as an exciting source. All bands predicted by group theory have been observed and their assignments made on the basis of the polarisation data and of the frequency shifts on deuteration. The doubly degenerate translatory and roatory external modes are not completely mixed. | 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 | 7,955 |
Real-world use of first-line chemotherapy in post-menopausal patients with HR-positive HER2-negative metastatic breast cancer (mBC) in a US community oncology network. | 561Background: Endocrine therapy (ET) is recommended as 1st line of therapy (LOT) for patients (pts) with HR+/HER2- mBC. Chemotherapy (CT), however, has also been used, though wide practice variation exists. The purpose of this study was to understand the utilization of 1st line CT and its toxicities for HR+/HER2- mBC in a US community oncology setting. Methods: A retrospective study was conducted using US Oncology’s iKnowMed electronic health record database, supplemented with chart review. Post-menopausal women with a diagnosis of HR+/HER2- mBC between Jan. 2010 and Dec. 2013 who received CT as the 1st therapy within 90 days after diagnosis were included. Pts were followed through Dec. 2014 or their last visit. CT regimens and toxicities were analyzed. Results: Of the 8,953 post-menopausal mBC pts, 39.4% (n = 3,525) received at least one CT agent within 90 days after diagnosis. Among those, 598 pts met all inclusion criteria with a final sample of 150 pts, verified by chart review, for analysis. The maj... | We report on active control of the femtosecond photodissociation and ionization reactions of iron pentacarbonyl, Fe(CO)5, in the gas phase. The spectral phase of femtosecond laser pulses is modified in a pulse shaper, employing a learning evolutionary algorithm. Direct feedback from the experiment is used to iteratively improve the laser pulse shape according to a given optimization problem. This many-parameter optimization is compared with one-parameter control schemes and found to be more versatile, because it can sample a much more general search space. Information about the underlying reaction mechanism can be extracted from the results of the automated optimization. It is further shown that second-harmonic generation (SHG) can be used at the output of a 800 nm pulse shaper to implement 400 nm excitation experiments. The optimization procedure not simply increases the SHG efficiency but optimizes the objective given for the combined system of SHG and Fe(CO)5 photochemistry. The importance of the choic... | eng_Latn | 7,956 |
Microscopic modelling of bulk and quantum-well GaAs-based semiconductor lasers | The dynamical behaviour of Fabry-Perot type semiconductor lasers is modelled, including the relevant many-body Coulomb effects of the excited carriers. Conditions are given under which a parametrization of the full model is possible, allowing simple analytic relations for local gain, refractive index and linewidth enhancement factor. The parameters of the simplified model are uniquely determined by the microscopic theory and have to be optimized for the respective operating conditions. The theory is evaluated for bulk and quantum-well GaAs active material and a variety of laser structures, including strongly and weakly index-guided structures, as well as purely guided single-and twin-stripe lasers. | This paper explores the effect of a partial-pattern receiver for transmitted orbital angular momentum (OAM) multimodes included in the Laguerre-Gaussian beam propagating under non-Kolomogorov weak-to-moderate turbulence on the achievable capacity and the error rates with introduced controlled parameters. We deduce the necessary conditions for reducing the receiver’s area to guarantee that the modes are decoupled when the area is reduced. Furthermore, we derive the conditions at which area reduction yields a performance gain over the complete-area reception. For that, some use cases are introduced and discussed and the basic building block for multibeam MIMO receivers with a reduced area is developed and analyzed. | eng_Latn | 7,957 |
The Development of High-Power Fiber Laser and Its Applications | The technology of fiber lasers is one of research focuses topics in current optoelectronic area,especially for a high-power fiber optic laser that has exhibited a tendency substituting traditional solid state laser and CO2 laser in many areas.We fully expound its principles and some key technologies from its structure,emphasize the technology of a pulse fiber optic laser that is more widely applied, and enumerate its superiorities and applications in such areas industrial processing,national defense,medical service,etc. | This paper proposes a novel scheme integrating full-duplex data communication into a wireless power transfer system. The power and data are transmitted on the same inductive link comprised of two coreless coils with taps. Frequency division multiplexing (FDM) technique is applied. The power and data are transmitted by using different frequency carriers. The duplexers are designed to implement full-duplex communication. The circuit model of the system is provided to analyze the power and data transfer performance. The crosstalk interference between power and data carriers is discussed. Finally, a prototype has been built to demonstrate the effectiveness of the proposed system. | eng_Latn | 7,958 |
Fast switching between continuous-wave and passively mode-locked regimes of Nd:YVO4 and Cr:LiSAF lasers | Many applications, including photo-poration of trapped cells, optical tweezing or chemical analysis, would benefit from a versatile, user-friendly laser, which could be able to be controllably switched between its continuous-wave (cw and cw mode-locked (ML)) regimes on short time scales, and also have its pulse parameters varied arbitrarily. We present the use of an optically-pumped saturable absorber (SA) inside Nd:YVO 4 and Cr:LiSAF lasers as a viable method to remotely control the laser mode of operation. | The level dyeing behavior of reactive dyes for soybean fibers was discussed from the point of view of the fixation rate curve, relative fixation rate and migrat ion behavior. The results show that the reactive dyes(e.g. Cibacron LS) of high substantivity and activity exhibit poorer migration, higher fixation percent and poorer levelness before the addition of alkali, and exhibit slower fixation rat e and better levelness after the addition of alkali than those of low substantiv ity(e.g. Levafix CA and Megafix B). The methods increasing the dyeing levelness were suggested for the reactive dyes of different migrating properties and fixat ion rates. | eng_Latn | 7,959 |
LASSO tuning parameter selection | The LASSO is a penalized regression method which simultaneously performs shrinkage and variable selection. The output produced by the LASSO consists of a piecewise linear solution path, starting with the null model and ending with the full least squares fit, as the value of a tuning parameter is decreased. The performance of the selected model therefore depends greatly on the choice of this parameter. This paper attempts to provide an overview of methods which are available to select the value of the tuning parameter for either prediction or variable selection purposes. A simulation study provides a comparison of these methods and assesses their performance. | -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 | 7,960 |
Light-emitting diode driving circuit with wide operating voltage range | The invention discloses a light-emitting diode driving circuit with a wide operating voltage range. The light-emitting diode driving circuit comprises a current selection circuit which can be used for controlling current paths in a plurality of light-emitting units according to individual critical voltage and a plurality of groups of current limiting values corresponding to light-emitting diodes in a plurality of light-emitting units. | Recently large area avalanche photodiodes with high performance, narrow operation tolerances and high reliability became available. We report on some tests of their performance for the readout of fast scintillators. > | eng_Latn | 7,961 |
Realization of Light Marks with Intensive Light Pulses | This paper puts forward a new way to use highly intensive light pulses to produce or extract light marks and describes the principles of the production and extraction of light marks. | We report carrier lifetime reduction in GaInAs/InP multiple quantum wells from 3Ons to 95ps using mesas with ion implantation of the sidewalls.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | eng_Latn | 7,962 |
Noise properties in multi-heterodyne spectrometers based on quantum- and interband-cascade lasers | The noise properties of two multi-heterodyne spectrometers based on multi-mode semiconductor lasers (QCLs and ICLs) are investigated to determine their detection performance limitations. Both laser technologies provide well-defined multi-heterodyne beat-note structures suitable for spectroscopic measurements. | A simple high-speed low input impedance CMOS current comparator is proposed. The circuit uses improved Wilson current-mirror to perform a subtraction. Negative feedback is employed to reduce the input impedance of the circuit. HSPICE is used to verify the circuit performance with a standard 0.5/spl mu/m CMOS technology. Simulation results demonstrate the propagation delay of 1.02 ns, average power consumption of 0.911 mW and input impedance of 137 /spl Omega/ for /spl plusmn/0.1/spl mu/A input current at the supply voltage of 3V. | eng_Latn | 7,963 |
Experimental study of CO2 laser welding inside a groove— Application to high thickness laser welding | Laser welding inside a groove has to be considered when a high thickness material is welded. The use of a groove shape allows the access of the laser beam to the lower part of the groove. The choice of the groove geometry (groove width, depth, or aperture angle), as well as the assist gas setup (leading, trailing or backside protection) are then significant operating parameters for the process control. In this study, U- and V-shaped groove welding with a CO2 laser was investigated. The U-shaped groove welding generates an increase in penetration depth, a very strong reduction of the process noise and of the plasma plume volume, compared to a bead on plate or a V-shaped groove welding. Also, the penetration depth for a U-groove welding is 20% greater than for a V groove. The groove geometry and the surface tension effects are determinant for these improvements. The influence of shielding gas shows that a trailing protection (gas flow emitted from the nozzle towards the welding direction) should be adopted ... | A tunable wavelength filter was proposed and demonstrated by using the ultraviolet nanoimprint technique. It consists of a Bragg grating in polymer waveguides and a heating electrode. The creation of the grating was substantially simplified with the introduction of a smart imprint stamp containing a waveguide pattern integrated with the grating pattern. The center wavelength of the filter was successfully tuned by taking advantage of the thermooptic effect in polymers, which was induced by supplying electrical power to the electrode. For the fabricated device, a transmission dip of ∼15dB and a 3dB bandwidth of 0.8nm were obtained at the Bragg wavelength of ∼1560nm. The achieved thermooptic tuning rate was ∼0.28nm∕mW, while the center wavelength was shifted from 1560nm to 1558nm with the electrical power consumption of 7mW. | eng_Latn | 7,964 |
Design And Optimization Of Planar Waveguide Magic Tee At W-band | Conventionally, the sum and difference signals of a tracking system are fixed up by sum and difference network and the network is often composed of four or more magic tees whose arms direct at four different directions, which give inconveniences to assemble. In this paper, a waveguide side-wall slot directional coupler and a double dielectric slab filled waveguide phase shifter is used to form a planar magic tee with four arms in the same H-plane. Four planar magic tees can be used to construct the W-band planar monopulse comparator. The planar magic tee is analyzed exactly with Ansoft HFSS software, and is optimized by genetic algorithm. Simulation results are presented, which show good performance. | Using ultrafast optical-pump terahertz-probe spectroscopy, we study the THz dynamics and electronic cooling in few-layer epitaxial and CVD graphene; a microscopic theory of carrier-carrier and carrier-phonon interactions accounts quantitatively for the observed dynamics. | kor_Hang | 7,965 |
Optic Nerve Head Drusen in Goldenhar Syndrome | We report a case where bilateral drusen of the optic nerve head was found in association with Goldenhar syndrome and which, to the best of our knowledge, is the only report of its kind. | We present optically pumped lasing from group IV GeSn/SiGeSn heterostructures. A comparison between double heterostructure and multi-quantum-well microdisk cavities reveals advantages of the multi-well design. Strongly reduced lasing thresholds compared to values from bulk devices are observed. | eng_Latn | 7,966 |
[The characteristics of the limbic-diencephalic disorders in patients with early forms of cerebral circulatory disturbances]. | The limbic and diencephalic disorders observed in patients with prestroke forms of cerebrovascular disturbances depend on clinical forms of cerebral circulation. Timely therapy is conducive to a more favourable course of cerebrovascular disturbances. | In a visible light communications (VLC) system, the frequency response of the light-emitting diode (LED) limits the signal bandwidth and, thus, becomes the bottleneck of the transmission data rate. The recent technology breakthrough of the micro-LED array has the potential to improve the modulation bandwidth of the LED by ten times. On the other hand, the nonlinearity of the micro-LED array is significant. Nonlinear distortion degrades system performance in both the achievable data rate and the transmission range. In this paper, we propose a digitally controlled micro-LED array architecture for the VLC system, which enjoys the benefit of wide modulation bandwidth of the micro-LED array and avoids the disadvantage of the nonlinear distortion. Compared with existing multiple LED structures, the proposed micro-LED array architecture shows robustness against nonlinear distortion. | eng_Latn | 7,967 |
Chirping compensation using a two-section semiconductor laser amplifier | Compensation of light source chirping and optical fiber dispersion using semiconductor laser amplifiers (SLAs) is investigated using a modeling equation that describes the opposite phase characteristics of light sources to SLAs with self phase modulation. A two-section SLA was fabricated in order to achieve an amplifier with both high gain and phase compensation properties. Preliminary experimental results are presented, confirming the theoretically derived phase compensation effect. > | AbstractThe apparatus developed in our department for electrocochleography is described. The principle of enhancement of a weak biological signal from background noise by an average response computer is elucidated, with indication of the limitations. The frequency content of the effective tone-burst sound stimulus was calculated to estimate the frequency specificity of the stimulus.A description is also given of the signal switching circuitry used to make separate recordings of CM and AP simultaneously. Some details are given of a circuit permitting rapid determination of AP threshold values and input-output curves with tone-bursts.Because the apparatus was developed to be applicable for experimental work and for auditory evoked response audiometry, several special features were incorporated. A circuit for accurate measurement of latency, a double-synchronized tone-burst generator, and a dB-linear intensity ramp with I’M bursts are briefly described.A flexible trigger generator provides many trigger modes... | eng_Latn | 7,968 |
KR desulphurization stirring device | The utility model discloses a stirring device, and particularly discloses a KR desulphurization stirring device which belongs to the technical field of metallurgic production equipment. During the use of equipment, a half-connection handle and a main shaft of the KR desulphurization stirring device are connected firmly. The desulphurization stirring device comprises the main shaft and the half-connection handle which is sheathed at the end of the main shaft; and the half-connection handle is sheathed with the end of the main shaft through an interference fit structure. | Since their discovery microresonator-based frequency combs have drawn a lot of interest due to their compact form factor and potential for integration. We report on the recent progress regarding dissipative Kerr solitons generated from photonic chip-based microresonators and their use in different fields of application. | eng_Latn | 7,969 |
Perspectives of$rm Nb_3rm Sn$in Future Accelerator Magnets | Upgrades presently being planned for high-energy hadron colliders require magnet performance beyond the capabilities of NbTi superconducting wire. Recent improvements in the performance of Nb3 Sn material and in the capability to use it in practical magnets make it the logical choice for the next generation of accelerator magnets. We discuss recent results of R&D programs, some remaining issues and possible solutions. Recent progress in understanding and in technical details of design and assembly have made Nb3Sn magnets easier to fabricate and more reliable in performance | An apertureless near-field scanning optical microscope (a-NSOM) setup is described. Special ::: consideration is given to important system components. Surface plasmons are defined, as is their relationship to a- ::: NSOM and their interaction with the scanning probe tip. We used this set-up to measure a metal-dielectric-metal ::: (MDM) antenna integrated with a quantum cascade laser (QCL). The former is introduced and described. The role ::: of the atomic force microscope (AFM) in the experiment is laid out and explained. Finally, the lock-in amplifier is ::: explained. Next, the system setup is introduced and explained from the point of view of the light path taken by ::: light generated in the laser. Finally, results are given for the MDM single nanorod antenna and the coupled MDM ::: nanorod antenna. Simulation, topography, and NSOM images are shown. Lastly, several experimental issues are ::: discussed as well as other types of NSOM. | kor_Hang | 7,970 |
New high-efficiency biscoumarin laser dyes | 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. | 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 | 7,971 |
New CW lines from a submillimeter waveguide laser | Sixty-one new CW laser lines with wavelengths between 0.1 and 1.5 mm have been observed with a waveguide laser optically pumped by a CO 2 laser. | Method and system for luminescence molecular imaging or tomographic attention region in the scattering medium are disclosed. The system includes a non-linear luminescent marker material disposed in the scattering medium. Thereby, the contrast and resolution of the imaging or tomographic imaging is improved. Nonlinear markers, for example, configured to up-convert the incident light of the illumination wavelength. The non-linear power dependency marker, allowing further improvement of imaging by using an image obtained using two or more excitation beams simultaneously. | eng_Latn | 7,972 |
Design, optimization and fabrication of an optical mode filter for integrated optics | We present the design, optimization, fabrication and characterization of an optical mode filter, which attenuates the snaking behavior of light caused by a lateral misalignment of the input optical fiber relative to an optical circuit. The mode filter is realized as a bottleneck section inserted in an optical waveguide in front of a branching element. It is designed with Bezier curves. Its effect, which depends on the optical state of polarization, is experimentally demonstrated by investigating the equilibrium of an optical splitter, which is greatly improved however only in TM mode. The measured optical losses induced by the filter are 0.28 dB. | This paper explains the way how to use the opto-coupler of interface grade with SPI bus in the control system in order to strengthen the noise rejection feature of the system. | eng_Latn | 7,973 |
A Monochromatic Black and White Supertwisted Nematic Liquid Crystal Display with a Single Cell and a Birefringent Film | To achieve a monochromatic black-and-white (B/W) STN-LCD with a single cell and a birefringent plastic film, the optimum conditions of optical properties in the birefringent film are analyzed theoretically and experimentally. By optimizing the film retardation to minimize the transmission of a STN-LCD at 550 nm, optical retardation in a STN cell is canceled and a B/W STN-LCD is obtained. By selecting the suitable conditions for compensating retardation of the STN cell, a B/W STN-LCD is achieved with the contrast ratio of 10:1. | We present the first nonlinear-mirror modelocked thin-disk laser, delivering 21 W at 323 fs pulse duration. This opens a new chapter for the nonlinear-mirror technique which, until now, only modelocked few-ps bulk oscillators. | eng_Latn | 7,974 |
Q-switched mode-locking and dissipative soliton operations in a large-anomalous-dispersion fiber laser | We have experimentally observed the Q-switched mode-locking (QML) and dissipative soliton operations in the passively mode-locked fiber laser operating in large-anomalous-dispersion regime. With the increase of pump power, the proposed fiber laser gradually evolves from continuous-wave to QML and finally to dissipative soliton operations. The transition state between QML and dissipative solitons has been observed. The experimental results suggest that the fiber laser based on the nonlinear polarization rotation technique exhibits Q-switching instabilities. | Abstract The burning history of a spherical diffusion flame element (Lagrangian flamelet) is modeled under three distinctive burning conditions: a quasi-steady burning process, a quasi-periodic burning mode, and a purely transient burning condition. In the quasi-periodic burning mode, the time scale of the oscillations is shown to affect the chemistry by providing an observed extinction reignition process associated with the unsteady fuel flux into the flame sheet. For the purely transient burning process radiation extinction occurs for certain soot loadings, initial fuel element sizes, and environmental temperatures. | eng_Latn | 7,975 |
Kinetics of O2(1Δg) photo-oxidation reactions in egg-yolk lecithin vesicles | The photosensitized oxidation of single bilayer vesicles of egg-yolk lecithin by singlet oxygen is investigated. The isotopic enhanced lifetime of singlet oxygen in heavy water, and the inhibitory effect of azide ions, are both used to examine the O2(1Δg) diffusion characteristics. The rate of photo-oxidation of unsaturated fatty acid is shown to be strongly dependent on the precise location of the sensitizer in the bilayer. Rate constants for the interaction of singlet oxygen with the lipid, with the acceptor 9,10-dimethylanthracene and with azide are determined to be 7.5 × 105, 3.2 × 108 and 1.0 × 108 dm3 mol–1 s–1, respectively. | As the key apparatus in ASON(Automatic Switched Optical Networks),the All Optical Wavelength Conversion(AOWC) device will take a very important effect.In this paper,based on the theoretical model of wavelength conversion in semiconductor laser,the influence of different photons life on wavelength conversion is discussed by utilizing rate equation under the small-signal analysis.Using FBG-ECL(Fiber Bragg Grating External Cavity semiconductor Laser) and DFB-LD(Distributed FeedBack-Laser Diode),the characteristics of wavelength conversion are discussed and analyzed by experiments in different signal rate and extinction ratio.The result is accordant with theoretical analysis.In conclusion,optimizing semiconductor laser's structure,and reducing photons life are very important to realize high speed all optical wavelength conversion. | eng_Latn | 7,976 |
Gain Narrowing in Few-Atom Systems | Using a density matrix approach, we study the simplest systems that display both gain and feedback: clusters of 2 to 5 atoms, one of which is pumped. The other atoms supply feedback through multiple scattering of light. We show that, if the atoms are in each other's near field, the system exhibits large gain narrowing and spectral mode redistribution. The observed phenomena are more pronounced if the feedback is enhanced. Our system is to our knowledge the simplest exactly solvable microscopic system which shows the approach to laser oscillation. | This paper analyses the causationes that influence the precision of the weighing system.Introduces the characteristics of the chip ADS1230 and designing of hardware circuit in weighing system.This design uses the most extensive and mature technology AT89C51 chip microcontroller and the resistance strain weighing sensor chip.The system has many characteristics-rapid weighing,exact and steady data,ease using,high anti-jamming ability etc. | eng_Latn | 7,977 |
Picosecond pulse operation of a dye laser containing a phase-conjugate mirror | We have demonstrated picosecond pulse operation of a synchronously pumped cw dye laser in which one of the conventional laser mirrors is replaced by an internally self-pumped BaTiO3 phase-conjugate mirror. The laser pulses, of about 15-psec duration, were close to transform-limited. This Letter represents the first report to our knowledge of steady-state picosecond pulse operation of a laser containing a phase-conjugate reflector. | 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 | 7,978 |
Linewidth measurements of tunable diode lasers using heterodyne and etalon techniques | Measurements of the linewidths of Pb–salt diode lasers operating in the 8- and 9-μm region are reported. The linewidths of the 9-μm lasers were determined by conventional heterodyne techniques, while for the 8-μm lasers a new technique based on a Fabry-Perot etalon was used. The new technique avoids the complexity and limited wavelength range of the heterodyne measurements and can be used for any tunable laser. The linewidths observed varied from 0.6- to >500-MHz FWHM. The linewidth was found to vary dramatically from device to device, to depend strongly on junction temperature and injection current, and to be correlated with vibrations caused by operation of a closed-cycle refrigerator. | A dynamic wavelength and bandwidth allocation (DWBA) algorithm based on linear prediction( LP-DWBA) to schedule resources in TWDM-PON is proposed. Simulation results show that LP-DWBA can reduce the average end-to-end delay of networks greatly compared with the existing schemes. | eng_Latn | 7,979 |
Research on Wavelet Neural Networks and Its Application to Sensor Reverse Modeling | details of initial, construction and parameters determine for a fast-converging discrete binary wavelet neural networks (WNN) has been introduced. This kind of WNN is used in sensors non-liner error correction and a simulation result is given. Compare to other neural networks trained by stochastic gradient method, theory of discrete binary wavelet transform speeds up the training procedure of fast-converging WNN and makes this WNN avoid converging to a local maximum point. This fast version of wavelet neural network is also not complicate in building. It solved the problem of slow convergence of dilation and translation parameters which caused by differentiating wavelets. | Smart windows with controllable visible and near-infrared light transmittance can significantly improve the building’s energy efficiency and inhabitant comfort. However, most of the current smart window technology cannot achieve the target of ideal solar control. Herein, we present a novel all-solution-processed hybrid micronano composite smart material that have four optical states to separately modulate the visible and NIR light transmittance through voltage and temperature, respectively. This dual-band optical modulation was achieved by constructing a phase-separated polymer framework, which contains the microsized liquid crystals domains with a negative dielectric constant and tungsten-doped vanadium dioxide (W-VO2) nanocrystals (NCs). The film with 2.5 wt % W-VO2 NCs exhibits transparency at normal condition, and the passage of visible light can be reversibly and actively regulated between 60.8% and 1.3% by external applied voltage. Also, the transmittance of NIR light can be reversibly and passively... | eng_Latn | 7,980 |
Tendency to Utilization of Optical Interconnection in Computer | The significations of "optical interconnections" are the theory and technology for data and signals transmitting and switching realized by the phenomena of the reciprocity of light wave-particle duality with substance. We summarized its features, the general-purpose in the academia, physical gist, technical property, necessity and feasibility, and discussed some top end technologies in interconnections: micro-electro-mechanical system switches and electroholographic switching used in interconnection, space/wave division multiplexing synchronous broadcast-and-select switch system for supercomputer and clusters. | This paper explains the way how to use the opto-coupler of interface grade with SPI bus in the control system in order to strengthen the noise rejection feature of the system. | eng_Latn | 7,981 |
Control of "Zero Window" for Launch CE-1 Satellite | Aiming at the launch of CE-1 satellite,the paper analyses the restricting factor and constitutes the plan controlling of "zero window" for launch CE-1 satellite from organizing and commanding,weather ensuring,controlling of key nodes,launch precaution plan and preview for urgency.It was used effective in the task,and insured the success of launch CE-1 satellite. | 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 | 7,982 |
Optical transmitter system and method | The present invention provides an optical duobinary transmitter system and method using optical intensity modulation. Such system comprising: an input terminal (51) for receiving a first binary signal; a driving circuit connected to the input terminal (53) for converting the binary signal into a first and a second a third binary signal; double electrode optical modulator (55) connected to a drive circuit, connected to its upper and lower electrodes may be respectively driven by said second and third binary signal, said modulated the drive is configured in accordance with a binary modulating an optical carrier signal amplitude and phase, thereby providing a binary signal with the respective first predetermined negative modulation chirp parameter having an optical duobinary signal; and a light modulator an output terminal (57) connected to the modulated optical duobinary signal is fed to the optical transmission line. The modulator may also be configured with a quasi-ternary signal driver. | Abstract In this paper, we study a general problem of optimal error reduction in linear multivariable systems. We show how a symptotic regulation can be achieved along with minimization of the H∞ norm of the error transfer function matrix. These resulte are of significance in the development of a new approach to the design of multivariable control systems. | eng_Latn | 7,983 |
2D and 3D heterogeneous photonic integrated circuits | Exponential increases in the amount of data that need to be sensed, communicated, and processed are continuing to drive the complexity of our computing, networking, and sensing systems. High degrees of integration is essential in scalable, practical, and cost-effective microsystems. In electronics, high-density 2D integration has naturally evolved towards 3D integration by stacking of memory and processor chips with through-silicon-vias. In photonics, too, we anticipate highdegrees of 3D integration of photonic components to become a prevailing method in realizing future microsystems for information and communication technologies. However, compared to electronics, photonic 3D integration face a number of challenges. This paper will review two methods of 3D photonic integration --- fs laser inscription and layer stacking, and discuss applications and future prospects. | 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 | 7,984 |
Development of a pulsed quantum cascade laser based CO sensor using advanced signal processing techniques | A pulsed, thermoelectrically cooled 4.6 /spl mu/m DFB-QCL CO sensor, incorporating a 100 m multipass cell and HgCdTe detector, is used to evaluate various processing schemes and their effects on temporal resolution, sensitivity, and selectivity of the spectrometer. | Abstract In this work, we are concerned with the experimental implementation of linear adaptive predictive control algorithms over a continuous fermentation process. The regulation and tracking problem of the substrate concentration is considered. Our objective is to shown their advantages and drawbacks in terms of tracking and regulation behaviour, overtaking, number of tuning parameters. The two controllers described in this paper are Linear Quadratic Control law and Long - Range Predictive Control law with partial state reference model. | eng_Latn | 7,985 |
Resonant electro-optical modulator for high laser-power single-mode fiber relay | We describe the design and performance of a resonant electro-optical modulator, based on stoichiometric lithium tantalate, capable of handling high optical powers and providing a large modulation depth. This phase modulator is part of the single-mode fiber relay used in the ESO VLT Laser Guide Star Facility for adaptive optics to transport 589-nm laser light from the PARSEC dye laser installed in the laser clean room to the laser launch telescope. The purpose of the phase modulator is to broaden the single-frequency PARSEC laser linewidth before the laser light is injected into the single-mode relay fiber. By this the power handling capability of the single-mode fiber is increased by a factor of 3 or 10 W of in-coupled power at 589 nm, while maintaining the excitation efficiency of the mesospheric sodium D2 transition. | We report the observation of inhibited spontaneous emission of organic dye rhodamine 6G infiltrated in a polymer replica of synthetic opal as a photonic crystal. The morphology-dependent resonances, superimposed on the broadband emission of rhodamine 6G due to spherical wavelength-sized microcavity enhancement of dye emission, have also been observed. | eng_Latn | 7,986 |
Soft X-ray Streak Camera with Dynamic Range of 2000 and Picosecond Temporal Resolution | A new streak camera with more wider dynamic range and picosecond temporal resolution for soft X-ray was developed.The photocathode′s working area is 30 mm in diameter,and its focusing voltage is reduced to 8 kV to prevent electrical discharge.A post-accelaration system was introduced into the image tube for improving the phosphor screen′s quantum efficiency largely,and an external image intensifier with wide dynamic range was adopted.Experimental evaluation was carried out by means of a picosecond laser,and the results show that the dynamic range of more than 2000 can be achieved. | We show that one can optically control the photoresponse of semiconductor devices by the phase of the EM incident radiation. This can be achieved by interfering two phase-locked quantum pathways, both projecting the same initial bound state to the same energy level in the continuum. An experimental study on quantum well infrared photodectectors is presented. | eng_Latn | 7,987 |
Overlapping Discs Filtration in the Commutative Operad | The spaces of configurations of non-$k$-overlapping discs have been studied as a bimodule over the little discs operad. In fact, the spaces form a filtered operad. We define and study the induced structure on the homology. | Concatenated optical coding provides channel grouping ability on OCDM networks. With the 16-chip optical code concatenating two 4-chip Fourier codes, selection of a channel in sixteen or a code group in four is experimentally demonstrated. | eng_Latn | 7,988 |
High-speed InP/InGaAsP/InGaAs avalanche photodiodes | High-speed operation of a long-wavelength (1.0µm ≲ λ ≲ 1.65µm) avalanche photodiode (APD) has been achieved with a heterojunction structure consisting of a wide-bandgap (InP) multiplication region and a narrow-bandgap (InGaAs) absorption region separated by an intermediate-bandgap (InGaAsP) "grading" layer. Previous InP/InGaAs APD's without the "grading" layer (SAM-APD structure) have exhibited low dark current and high avalanche gain, but they have not performed well at high bit rates because the bandwidth is restricted by hole trapping at the valence band discontinuity of the InP/InGaAs interface. In this paper we demonstrate that the incorporation of a "grading" layer results in a dramatic improvement in the speed of response while maintaining low dark current, good quantum efficiency, and high avalanche gain. By incorporating one of these APD's into a high-speed optical receiver, sensitivity measurements have been obtained for 1.3µm and 1.5µm wavelengths at bit rates of 420 Mb/s and 1 Gb/s. | We present the first ultrafast all-optical switching measurements of photonic band gap crystals at telecom frequencies. Switching 3D photonic band gap crystals is expected to provide dynamic control of active photonic integrated circuits, over the switching-on or -off of light sources, and the capture or release of photons from photonic band gap cavities. | kor_Hang | 7,989 |
High-throughput of single high-power laser pulses by hollow photonic band gap fibers | We report the delivery of high-energy nanosecond pulses (10 ns pulse width) from a Q-switched Nd:YAG laser through the fundamental mode of a hollow-core photonic crystal fiber at 1064 nm. At a pressure of 450 mbar, energies greater than 1 mJ were delivered in a single spatial mode through the hollow-core fiber, coupling efficiencies over 80% were demonstrated. | We consider physical conditions for realizing the Bragg regime of one-, two-, and three-phonon scattering of light in optically anisotropic crystalline materials. The exact and closed analytical models for describing these regimes are developed and solved. The performed analysis takes into account an opportunity of realizing 100% efficiency of light scattering in these regimes. Possible applications lie in the fields of creating large-aperture modulators of light. In connection with this, the problems of optimizing the frequency bandwidths and potential resolution of such modulators are studied. Reasonable attention is paid to the contribution of acoustic anisotropy to frequency bandwidth. The analytical results are illustrated by computer simulations and compared with proof-of-principle experimental data related to a multi-phonon light scattering in a tellurium dioxide crystal. | eng_Latn | 7,990 |
Lin || lin coherent population trapping and its application for vapor-cell-atomic-clocks | The authors presented investigations on the application of CPT effect as alternative to the traditional optical microwave double resonance in small atomic clocks. An important factor which may limit the performances of CPT-based atomic clocks is the reduced signal contrast as compared to optical pumping. To overcome this limit, several excitation schemes have been proposed in the last years. Particularly, a significant enhancement of the CPT contrast can be obtained when co-propagating laser waves with parallel linear polarization (lin | | lin CPT) are resonant with the excited state Fe=l of alkali atoms. | This paper presents a modeling approach based on chanceconstrained programming, that determines least‐cost time‐linked air pollution emission controls, while accounting for the dynamic and stochastic character of meteorological conditions and respecting different averaging‐time ambient air quality standards with exogenously specified reliabilities. The methodology is numerically illustrated with actual meteorological data in the case of an isolated pollution source and of monthly and annual air quality standards. Areas for further research are also delineated. | eng_Latn | 7,991 |
DEVELOPMENT OF A BEAM LOSS MEASUREMENT SYSTEM WITH GIGABIT ETHERNET READOUT AT CERN | The aim of the BLM Dual Polarity module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. In its default configuration, it is expected to provide data to the processing electronics through two point-to-point connections with bidirectional multi-gigabit optical links. For the development phases as well as later serving as a standalone measurement system, its reconfigurable FPGA device is exploited to provide a soft-core CPU with a custom made server. This server, running on the CPU, will expose through the Gigabit Ethernet connection and the TCP/IP protocol different types of data in the network. In this paper the development of the system and of the communication protocol is explored as well as the accompanying client application that is realised with the purpose of commanding, collecting storing and viewing the different types of data. | Using a density matrix approach, we study the simplest systems that display both gain and feedback: clusters of 2 to 5 atoms, one of which is pumped. The other atoms supply feedback through multiple scattering of light. We show that, if the atoms are in each other's near field, the system exhibits large gain narrowing and spectral mode redistribution. The observed phenomena are more pronounced if the feedback is enhanced. Our system is to our knowledge the simplest exactly solvable microscopic system which shows the approach to laser oscillation. | yue_Hant | 7,992 |
Detection of messenger RNA using a digoxigenin end labelled oligodeoxynucleotide probe. | A synthetic oligodeoxynucleotide sequence complementary to the mRNA for the adrenocorticotrophin (ACTH) precursor pro-opiomelanocortin (POMC) was end labelled using digoxigenin. The probe was used to detect POMC mRNA both on nitrocellulose filters and by non-isotopic in situ hybridisation (NISH) in tissue sections. Digoxigenin was identified using anti-digoxigenin alkaline phosphatase. The model system examined was the rat pituitary gland. Removal of both adrenal glands and dexamethasone administration were used to change the concentrations of POMC mRNA in the rat anterior lobe. The labelled probe reacted with a single band of appropriate molecular weight in Northern blot analysis. The distribution of signal in tissue sections and the changes induced by experimental manipulation were as predicted. The results indicate that this method of NISH will prove useful in the detection of specific messenger RNAs in tissue sections of buffered, formalin fixed, paraffin wax embedded material. | 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 | 7,993 |
Self-adaptive thermal-lensing compensation for a high-power laser | In this study, we present the analytic temperature profile in cylindrical geometry for transmissive optics. The model permits the explicit calculation of the optical path length difference across the radial direction of a rod. This allows us to determine the specific length of the compensation material to remove the thermal effect not only for a small region at the beam’s center but also for the entire geometry of the optics, including high-order aberrations for various power ranges. | -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 | 7,994 |
Analysis and demonstration of single-passband response and tuning characteristics in a chirped ladder interferometric filter for a widely tunable laser diode. | 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. | 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. | eng_Latn | 7,995 |
A simulation of fiber distributed data interface for token ring lan protocols | The aim of this work has been to graphi cally simulate the protocols employed for 100 Mbps token ring local area network (LAN), using the fiber-optic medium, known as Fiber Distributed Data Interface (FDDI), and to study its performance evaluation. In the computer based simulation, the effort has been made to describe the working of the protocols using graphical, dynamically working models. Also performance characteristics, such as Throughput Vs Token rotation time, Throughput Vs Ring Latency, Throughput Vs Data Arrival Rate are obtained. The asynchronous priority level throughput for different data arrival times are tabulated. From the characteristics, it is found that the relative difference between the ring latency and the token rotation time (TRT) has a significant effect on the maximum total throughput. Also with the higher value of the TRT the throughput increases faster compared to lower TRT values. | This paper reports on the development of optically based techniques to detect and identify chemical agents. Detection ::: sensitivity and molecule discrimination are studied. In parallel, efforts are made to develop rugged and compact ::: experimental designs that can be used for field measurements. Laser Induced breakdown spectroscopy (LIBS) is a ::: surface analyzing optical technique investigated to measure sarin like molecules deposited on samples coming from the ::: Parisian subway. On the other hand, Tunable Diode Laser Spectroscopy (TDLS) - Cavity Ring-Down Spectroscopy ::: (CRDS) or Cavity Enhanced Absorption Spectroscopy (CEAS) - is used to measure traces of the industrial toxic ::: hydrogen fluoride gas down to the ppb level. Measurements in laboratory are reported and primary results obtained in a ::: field experiment are described. | eng_Latn | 7,996 |
Further studies of the methyl nitrite cis→trans isomerization | Classical trajectory calculations have been performed to get more insights into the dynamics of cis→trans isomerization of methyl nitrite. Harmonic (diagonal and nondiagonal) and anharmonic potential energy surfaces with parameter values based on the available experimental data and our own ab initio results have been used in these computations. The ab initio calculations have been carried out at the MP2 and QCISD levels of theory, employing the 6-311++G** basis set. Coupling of vibrational modes is analyzed in detail. The influence of molecular rotation and isotopic substitution on the isomerization rate is investigated. Mode specific effects are clearly exhibited for the diagonal-harmonic potential, but they are significantly reduced by inclusion of anharmonicity or interaction terms in the potential function. It is found that modes that exhibit specificity are coupled with the reaction coordinate and with other vibrational modes that couple with the reaction coordinate as well. A comparison of rate coef... | Abstract : The CSIR National Metrology Laboratory (CSIR-NML) is the custodian of the South African national measurement standards. The Time and Frequency (TF) Laboratory is responsible for the maintenance of the SI second, which is the most accurate standard currently maintained. In addition to the maintenance of the national timescale, the TF Laboratory is also responsible for a number of other parameters, including fast electrical pulse characterization, phase angle, phase noise, and a number of fiber-optic parameters. A project in which the TF Laboratory plans to take a leading role is establishing a frequency comb based on a femtosecond laser at the CSIR-NML. | eng_Latn | 7,997 |
Dispersion-managed soliton operation of Ti:sapphire laser oscillators | 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. | In fundamental solvent extraction research at Oak Ridge National Laboratory a large number of systems have been discovered that are selective for one or a few elements. Some of these have been adapted to analytical separation and assay. To serve our own need for highly reproducible and accurate analysis of samples containing ..cap alpha.. and ..beta..-emitting nuclides, we have turned to liquid scintillation in both its familiar ..beta..-liquid scintillation (..beta..-LS) form and in a less-familiar development called Photon-Electron Rejecting Alpha Liquid Scintillation (PERALS) spectrometry. ..beta.. counting by the former and ..cap alpha.. counting by the latter combined with appropriate separation method result in powerful tools for radioassay of a wide range of sample types. 15 refs. | eng_Latn | 7,998 |
Thermal contribution to wavelength switching characteristics of widely tunable lasers | Thermal effects on wavelength switching dynamics are investigated for a wideband laser. For frequency shift keying (FSK) applications it has been shown that the laser phase current must be switched every 30 ns or in other words modulated at over 35 MHz, to achieve full range frequency dither. Alternatively FSK as low as 5 MHz is possible with a 10% loss of frequency excursion. In this paper, thermal effects on the FSK modulation and wavelength switching dynamics are investigated for a grating-assisted co-directional coupler with sampled grating reflector (GCSR) laser with the phase section. | Abstract The burning history of a spherical diffusion flame element (Lagrangian flamelet) is modeled under three distinctive burning conditions: a quasi-steady burning process, a quasi-periodic burning mode, and a purely transient burning condition. In the quasi-periodic burning mode, the time scale of the oscillations is shown to affect the chemistry by providing an observed extinction reignition process associated with the unsteady fuel flux into the flame sheet. For the purely transient burning process radiation extinction occurs for certain soot loadings, initial fuel element sizes, and environmental temperatures. | eng_Latn | 7,999 |
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