A system is proposed to use BP neural network and Fresnel transform technique for computer-generated hologram compression. In experiments, this scheme is more robust and effective than DCT and DWT compression under lo...
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A system is proposed to use BP neural network and Fresnel transform technique for computer-generated hologram compression. In experiments, this scheme is more robust and effective than DCT and DWT compression under lo...
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A bandwidth enhancement method is presented for silicon-on-insulator waveguidebased wavelength conversion using nondegenerate four-wave mixing. The conversion bandwidth is broadened by 28% in a 300 × 500 nm2 wave...
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All-optical wavelength conversion is investigated using fourwave mixing in silicon waveguides. The influences of nonlinear losses caused by two-photon absorption (TPA) and TPA-induced free-carrier absorption on the co...
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ISBN:
(纸本)9781849193146
All-optical wavelength conversion is investigated using fourwave mixing in silicon waveguides. The influences of nonlinear losses caused by two-photon absorption (TPA) and TPA-induced free-carrier absorption on the conversion efficiency and phase-matching condition are analyzed. The conversion bandwidth is tempted to enhance by optimizing the waveguide geometry and using the two-pump regime. And finally an angled-polarization pump is used to realize the polarization-independent wavelength conversion by eliminating the polarization discrepancy between the TE and TM modes.
This paper presents a piezoelectric-metal structure called a drum transducer. An equation for calculating the resonance frequency of the drum transducer is obtained based on thin plate elastic theory of piezoelectric ...
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This paper presents a piezoelectric-metal structure called a drum transducer. An equation for calculating the resonance frequency of the drum transducer is obtained based on thin plate elastic theory of piezoelectric and metal material combined with the Rayleigh-Ritz method. The finite element method (FEM) was used to predict the excitation frequency of the drum transducer. To verify the theoretical analysis, the input impedance characteristic of the drum transducer was measured using an experimental method. The results obtained from theoretical analysis were in very good agreement with those from the FEM and experimental results. The effect of geometrical changes to the thick-walled steel ring of the drum transducer at the first resonance frequency is also described. The calculated results were found to be in good agreement with the FEM results. The results indicate that the first resonance frequency of the drum decreases with the increasing inner diameter of the thick-walled steel ring.
Contact thermal resistance existed in the contact face between light emitting diode(LED) substrate and heat sink, which could hinder thermal conducting from PN junction to heat sinks, when mounting high power LEDs(HP-...
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We report a novel system for highly stable 100 MHz mode locked pulse as a reference frequency signal transfer through a round trip 20 km urban fiber link. An electronic approach for compensating the fluctuations intro...
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We report a novel system for highly stable 100 MHz mode locked pulse as a reference frequency signal transfer through a round trip 20 km urban fiber link. An electronic approach for compensating the fluctuations introduced by the link is proposed and implemented. The rms phase fluctuation was reduced from 75 mrad (118 ps) to 4 mrad (6.3 ps) in 48 hours, and the frequency stability was improved by three orders of magnitude in the measurement time.
The theory of a laser system with a ladder-type configuration is studied in detail based on the quantum Langevin approach. By using an external field to link the lower lasing level with another atomic level, whose dec...
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The theory of a laser system with a ladder-type configuration is studied in detail based on the quantum Langevin approach. By using an external field to link the lower lasing level with another atomic level, whose decay rate is much larger, laser intensity significantly increases and the quantum-limited linewidth can be quenched. We also discuss the spectrum of fluctuations of the output field, and the result shows that the fluctuations at low frequencies can be much suppressed too. On the other hand, this quenching approach can realize a laser output between two atomic levels, whose decay rates do not satisfy the usual lasing condition that the decay rate of the lower lasing level should be larger than that of the upper lasing level. It will be very useful to realize a laser output with the wavelength we want. This quenching approach has been widely used in the absorption spectrum of the ytterbium optical lattice clock and in the laser cooling approach for calcium atoms. Here we apply it in the stimulated emission of lasers.
To balance the hydraulic and anti-clogging performances for labyrinth-channel emitters, a multi-objective optimization was performed to improve the structure of trapezoidal labyrinth channels. Two variables, pressure ...
To balance the hydraulic and anti-clogging performances for labyrinth-channel emitters, a multi-objective optimization was performed to improve the structure of trapezoidal labyrinth channels. Two variables, pressure loss coefficient (PLC) and passage rate of particles (PRP), were proposed to evaluate the hydraulic and anti-clogging performances, respectively. The Pareto fronts of PLC and PRP were calculated using the elitist non-dominated sorting genetic algorithm version II (NSGA-II). The results show that the optimal fronts are obtained through 100 generations evolution. The associated key parameters D/W and H/D are constant, while S/H and α are different for each front. In addition, the approach to obtain a trade-off solution from these fronts was developed by arranging different weights for the two variables. This approach is very suitable for structural optimization of labyrinth channels with the same shape but different dimensions.
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