Research On Four Channel Avalanche Photodiode Performance Testing System

Avalanche photodiode is the most important core device in the field of single photon detection at the receiving end of quantum communication.The single-photon detection device uses the characteristics of the avalanche photodiode to detect single-photons.because it have a high multiplication effect operating in the Geiger mode.The avalanche photodiode which working in Geiger mode is evaluated for detection efficiency,post-pulse,dark count.They directly affect the effect of single photon detection.Therefore,it is extremely important to test and verify the performance of avalanche photodiodes before the manufacture of single-photon detection equipment.This article develops a four-channel avalanche diode test system for performance parameters that avalanche photodiodes are most concerned about.The paper introduces the problems of current avalanche photodiode testing,such as redundant equipment and low test efficiency.The research and development requirements of the test system are proposed by studying the working principle of avalanche photodiodes.An avalanche photodiode performance test system with FPGA and high-precision time-to-digital conversion chip TDC-GPX as the core is designed The test system integrates a single photon source,The drive signal is generated by the system clock to drive the laser to emit light.Link attenuation is designed to realize the single-photon pulse output during the light transmission process and a negative feedback mechanism is introduced to ensure the stability of the output light intensity while monitoring the light intensity.The final output is four single-photon pulses with a frequency of 800 KHz and a light intensity of-91.93 d Bm.The time-based digital conversion chip realizes 27 ps high-precision data collection,which can effectively perform photon counting.The detection efficiency,post-pulse rate and dark count rate of APD can be obtained by statistically calculating the collected information.The test system adopts a four-channel multiplexing design scheme,which can complete the automatic test of the performance of 4 APDs at the same time,which improves the test efficiency of a single APD from 20 minutes to 5 minutes.