在使用时间关联单光子计数的量子保密通信、量子密码术等量子光学领域中，雪崩光电二极管(APD)拥有广泛的应用。然而在其工作过程中，吸收层接收到光子形成载流子，载流子个数在倍增层进行指数型增益，每个载流子通过P-N 结结点均有一定概率发出光子，发出的光子在一定条件下会串扰进入另一个雪崩二极管。在盖革模式下进行单光子探测时，这种串扰光子会严重影响时间关联单光子计数的实验结果。研究了APD 雪崩原理，实验中做出了串扰峰对比度比较高的现象，分析了影响串扰峰间距和形状的因素，提出通过光隔离规避串扰现象，并通过实验验证了这种避免串扰方法的可行性。

Avalanche photodiode (APD) has a wide range of applications for time- correlated single- photon counting in quantum secure communication, quantum cryptography, and other quantum optics fields. However, during APD operation, incident photons in the absorption layer create carriers, which then multiply exsponentially. As each carrier goes through the P-N junction node there is a certain probability that it will cause the emission of another photon. Under certain conditions this newly emitted photon can generate crosstalk in the other avalanche photodiode, thus affecting the time-correlated single-photon counting results when detecting single photons in the Geiger mode. Through experimentally reproducing the phenomenon of relatively high contrast crosstalk interference we analyze the factors influencing the crosstalk peak, including peak spacing and shape. A scheme using optical isolation is proposed to avoid the crosstalk, and its feasibility is verified experimentally.