单光子捕获技术是自由空间量子密钥分配的关键技术。单光子捕获概率是一个重要问题。基于厄米-高斯光束处于TEM20,TEM02,TEM30,TEM03及TEM11模式下的单光子捕获概率理论模型被建立,通过数值仿真给出厄米-高斯光束处于不同模式下单光子捕获概率的大小。以TEM10为例给出时间滤波的物理模型,将该模型与数值仿真结果相结合,分析在进行单光子捕获时需要被淘汰模式和最佳模式,并给出了TEM20模式下时间滤波的具体实现过程及其应用价值,从而达到对自由空间量子密钥分配系统的优化。

Single-photon acquisition is the key technology of free-space quantum key distribution. Single-photon acquisition probability is very important. Based Hermite-Gaussian beams in TEM20,TEM02,TEM30,TEM03 and TEM11,the theoretical model of single-photon acquisition probability is established. And the probability in different modes is shown by numerical simulation. The physical model of time filtering is established,the limited mode and optimal mode are analyzed. The results can provide theoretical basis for the design of single-photon source,and optimize the system of free-space quantum key distribution.