光束的偏振特性在大气传输中变化比较小，因而偏振移位键控调制具有较高的可靠性。以星地激光通信为背景，研究星地激光通信链路的圆偏振移位键控调制的误码率性能。考虑到大气湍流的影响，采用Hufnagle-Valley大气折射结构常数模型，在Rytov方差分别为0.082，1.11这两种弱、强湍流起伏条件下，通过对比圆偏振移位键控调制和直接检测开关键控调制的误码率，得到了同等湍流起伏条件下前者误码率性能比后者突出的结论。特别是Rytov方差为0.082时，要达到10-7的误码率，它们对信噪比的要求分别是21.65 dB和30 dB, 圆偏振移位键控调制对信噪比的要求降低了8.35 dB。此外，还分析了近地面折射结构常数、天顶角和地面风速这3个因素对误码率的影响，仿真结果表明圆偏振移位键控调制的误码率比直接检测开关键控调制最少降低2个数量级。因此，圆偏振移位键控调制在未来星地激光通信中有着广阔的发展前景。

The polarization shift keying modulation has high reliability since the polarization properties of beam light change relatively small while propagating through the atmoshpere. The bit error rate(BER) performace of the circle polarization shift keying modulation in the satellite-to-ground laser communication is studied. Considering the effects of the atmospheric turbulence, the Hufnagle-Valley refractive index structure constant mode is adopted. By comparing the BER performace of the circle polarization shift keying modulation and the on-off keying (OOK) modulation under the weak and strong turbulence fluctuation, with the values of the Rytov variance are 0.082 and 1.11, it comes to a conclusion that the former is superior to the latter on the BER performace.Especially when the BER of 10-7, is to be achieved, their signal to noise ratio are 21.65 dB and 30 dB, the circle polarization shift keying modulation reduces 8.35dB of the signal to noise ratio under the Rytov variance is 0.082.In addition, the effects on the BER of three factors,which are the near-surface refraction structure constant, the zenith angle and the ground wind speed are analyzed . The simulation results show that the BER of the circle polarization shift keying modulation is lower than the OOK modulation at least two magnitudes. Therefore, it has broad prospect in the satellite-to-ground laser communication in future.