| Single-photon detection technology has broad application prospects in low-light sensing applications that require high sensitivity,such as 3D lidar imaging technology,quantum key distribution,light sensing ranging technology and medical imaging technology.The most basic and core component in these applications is the Single Photon Avalanche Detector(SPAD).In single photon detection,the available light signal is very weak,and the weak photon signal must be detected by corresponding signal amplification.And at the same time maintain extremely low noise.SPAD needs to work in Geiger mode,the incident photon will cause a continuous avalanche current,and then the diode's peripheral circuit is used to quench the diode,finally achieve the purpose of detecting and counting a single photon.In recent years,single-photon detection technology has become more popular due to its lower cost,lower operating voltage,higher sensitivity,and smaller size.However,with the rapid rise and development of quantum information technology,people's performance requirements for single-photon detectors such as detection efficiency and measurement accuracy have also been further improved.In single-photon detection technology,parameters such as SPAD's bias voltage and quenching chip delay time can greatly affect the performance of the detector.At the same time,with the advancement of technology,the single-photon avalanche detector and its peripheral circuits are required to achieve a high degree of integration.These factors all pose challenges to the design and optimization of the single-photon counting system,and the existing structure also has some shortcomings.In order to solve this problem,this thesis has carried out a detailed study on the principle of SPAD and the factors affecting its performance,and designed a highly integrated single-photon counting system module with multi-parameter adjustable based on the single-chip microcomputer.The main work is as follows:First,a compact single-photon counting module that can accurately control the bias voltage and hold-off time is developed in this work.The module is a microcontroller-based system which mainly consists of a microcontroller,a programmable negative voltage generator,a silicon-based single-photon avalanche diode,and an integrated active quench and reset circuit.Users can directly control the bias voltage and delay time parameters through the upper computer software.At the same time,the system module can provide an adjustable reverse 14V?40V bias voltage with an accuracy of 0.4V;the delay time control can be controlled from a few nanoseconds to1.6us,the resolution is 6.3ns,and all components are integrated on a circuit board with the compact structure occupies a small volume.Then,the designed single-photon counting system module is used to carry out experimental detection of key parameters in various single-photon detection technologies.When the delay time is about 28.5ns,the counting system reaches saturation,and the photon counting rate reaches 35 MHz.When the bias voltage is controlled at 26.8V,the dark count of the system is about 200 times per second,and the time jitter value is about158 ps.The photon detection efficiency detection experiment results also show that the module is suitable for detecting short-wavelength light from 450 nm to 700 nm,and a peak quantum efficiency of 40% can be obtained at a wavelength of about 600 nm.Experiments show that the temperature of the system does not change significantly after a long time operation.After collating the experimental data,introducing the figures of merit,and found out the most suitable conditions for the operation of the single-photon detector. |
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