| In recent years,with the continuous development of quantum communication system,high-speed single photon detection technology and single photon detector have gradually become research hotspots.InGaAs/InP single photon avalanche photodiode(SPAD)and InGaAs/InAlAs SPAD are the core chips in near-infrared single photon detection system,and it is of great significance to study their performance.InGaAs/InP SPAD has the advantages of strong practicability and high reliability,which becomes the main choice to realize near-infrared single photon detection.While InGaAs/InAlAs SPAD has a larger gain-bandwidth product,which is more appropriate to be applied in high-speed single photon detection system,but there are few studies on the performance of InGaAs/InAlAs SPAD.And so far,the near-infrared single photon detection system still has the challenges of low photon detection efficiency,high dark count rate and afterpulse rate.This dissertation deeply investigates the challenges in the near-infrared single photon detection system.The specific research contents are as follows:(1)In order to reduce the dark count rate and afterpulse rate of the system,a GHz high-speed gated InGaAs/InAlAs single photon detection system is built.The system mainly includes optical and circuit design.The optical part is mainly the preparation of a single photon source.The circuit part mainly includes a gated quenching circuit,an amplifier circuit,a low-pass filter circuit,and a discrimination circuit.Based on the built system,this work has achieved following results.At normal temperature,when the sine wave gating frequency is 1.5 GHz,the maximum photon detection efficiency is 8.38%,and the corresponding dark count probability is 1.35×10-3/gate;when the sine wave gating frequency is 2.4 GHz,the maximum photon detection efficiency is 8.43%,and the corresponding dark count probability is 8.67×10-4/gate.In addition,the detection system has no obvious afterpulse phenomenon under high-speed gating.(2)In order to improve the overall performance of the system,a three-electrode lateral multiplication InGaAs/InP SPAD is designed.The device has the characteristics of high gain and low dark current.The gain is more than 6000 and the dark current is about 0.1 n A near the breakdown voltage.However,the bandwidth of the device is about 2 MHz,and it can only respond to low-speed single photon signals.The frequency response characteristic of this device is analyzed by establishing an equivalent circuit model,and it can be concluded that the RC time constant limits the bandwidth,which lays the foundation for further improving the device bandwidth.(3)In order to satisfy the requirements of high-speed single photon detection system,a high bandwidth lateral multiplication InGaAs/InP SPAD is further proposed.The simulation results show that the device also has the characteristics of high gain and low dark current,and the 3 d B bandwidth is about 4.1 GHz,which could respond to high-speed single photon signals. |
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