Papers by Keyword: APD

Abstract: In order to improve the detection distance of laser proximity fuze without increasing laser power, the capability of laser fuze receiving weak laser echo signal must be improved. An avalanche photodiode (APD), which had the advantages of high sensitivity, low noise, with inner gain, was used as photodetector in laser fuze system to improve the capability of laser fuze detecting weak signal. The equivalent noise model of APD photoelectric conversion was analyzed, and the low-noise preamplifier and voltage amplification circuit matching the avalanche photodiode were designed. The noise ratio and frequency bandwidth of amplification circuit were analyzed and calculated, also the simulation and experimental verification were accomplished. The results showed that the circuit has wide bandwidth and high signal to noise ratio,which meets the requirements of subsequent processing circuitry of laser fuze.

Abstract: To accurately and rapidly detect single-photons is of the utmost importance for a Chemiluminescence Immunoassay (CLIA) system. An APD-based detection module of single-photons is designed in this paper. By comparison with PMT, APD possesses the advantages of higher detection sensitivity, lower dark current, smaller size, lower power consumption and higher integrity. The designed module can accurately detect single-photons with 22MHz frequency. The experimental results show that the module can be a basis for designing portable CLIA systems.

Abstract: Aiming at the burst point time measuring device cannot timely show the burst point time measurement situation, a new measuring system was designed. The pulse signal when the ammo was outing of the muzzle and exploding was detected by APD, the light pulse was converted to voltage pulse through an amplifying circuit. The timing display module was designed, the timing circuit got the voltage pulse and timing, and then the burst point time would show on LCD. All the photoelectric detector module was fixed with the special mechanical properties. The system could increase the maximum detection distance effectively, improve its detecting precision, and display the burst point time immediately. With the simulation experiment, the system had no failing to get the burst point time, and owned a stable performance. This design can provide a reference for the optimization and improvement of the burst point time measuring device.

Abstract: The echo signal received by laser fuze was very weak when the detection range increased. In order to expand the operating range of fuze, the reception capacity of fuze for weak signal should be improved. According to the requirements of long-range laser fuze receiving system as small volume, low-power, low-noise, high-gain, the amplifying circuit of the receiving system was analyzed and designed. To improve the ability of laser fuze for detecting weak signal, the high-sensitive, low-noise, inner-gain avalanche photodiode (APD) was used as a photodetector in the system, and the low-noise preamplifier and voltage amplifying circuit was designed. The noise and frequency response of the amplifying circuit was researched and analyzed by simulation and experiment. The results show that the design is effective and feasible, which can meet the requirements of processing circuit as receiving weak signal from long-distance.

Abstract: We present the simulation results of the InGaAs/InP avalanche photodiode (APD). In the structure a 70 nm InGaAsP grade charge layer and a 70 nm InP charge layer between absorption and multiplication layer have been used for reducing the dark current and achieving higher avalanche gain. A 50 avalanche gain around 35 V breakdown voltages has obtained, which has enhanced by nearly 4 times than that of the conventional InGaAs/InP APD. It has been also shown that the dark current in the device can be significantly reduced nearly one order compared to the corresponding conventional one. The numerical simulation means may design the high gain and low breakdown voltage InGaAs/InP APD.

Abstract: D022-Ni3V contains three variants whose [001] c-axes are mutually perpendicular. In addition, due to the order-disorder transition the anti-phase domains (APD) are also introduced under some heat-treatment conditions. In this study, the influence of such microstructures; the size of variants and APDs, on the plastic deformation behavior of Ni3V was investigated by using single crystals, in which the microstructure was variously controlled by heat-treatments.

Abstract: We report on the fabrication and testing of SiC p-i-n avalanche photodiodes. APDs of 0.25 mm2 area on a-plane (1120) 6H-SiC as well as off-axis Si face 6H and 4H-SiC were successfully fabricated. A beveled mesa was used as edge termination. Recessed windows were formed using reactive ion etching to enhance low-wavelength UV performance. We performed current-voltage tests with and without UV illumination to determine dark current, photocurrent, and gain on selected devices. Dark current was less than 1 pA at 0.5Vbr on multiple devices. Quantum efficiency of 40% or greater was observed for all orientations and polytypes.