单光子雪崩二极管是一种采用盖革模式的单光子探测器件。一旦触发后探测器需要一段时间来重启, 重启之后才能进行下一个光子事件的探测。重启所用时间(也叫死时间)的大小会影响探测器的光子计数分布。对单光子雪崩二极管的工作方式进行了数学建模, 研究死时间对探测器输出响应的影响, 推导出了在入射光子数服从泊松分布情况下探测器光子计数值的概率分布函数, 并采用蒙特卡洛仿真进行了验证。结果表明死时间会使探测器输出的光子计数值减小, 其分布会更加集中, 并且死时间越大, 入射光子速率越高,这种效应就越明显。

Single photon avalanche diode (SPAD) is a detector with high quantum efficiency which is able to detect single photons. It works in a so-called Geiger mode which means once triggered SPAD must be reset to enable the detection of another event. Thus the performance of SPAD depends on the reset-time a.k.a. dead-time. The performance of SPAD with deadtime effects is investigated and an equation supported by Montecarlo simulation is developed to describe the distribution of SPAD detections with assumptions that the distribution of the signal is assumed to follow Poisson statistics. It shows that the photon counts will decrease with the increment of the deadtime.