利用数值模拟的方法,定量地计算分析了空间激光通信中光强起伏问题,得到了准直光束与聚焦光束光强起伏相关距离(不均匀元半径)随大气相干长度变化的结果;进而分别从接收效率和性价比等不同的角度对激光通信系统接收孔径选取的参考因素进行了探讨。根据现代光通信对误码率的最低要求定义最佳接收孔径,计算分析了聚焦光束空间激光通信系统最佳接收孔径随大气相干长度r0的变化关系。结果表明,最佳接收孔径随大气相干长度的减小而迅速增大。对于聚集光束空间激光通信而言,在大气相干长度r0约为4 cm的强湍流效应情况下,通信系统的接收孔径接近5倍艾里斑直径,才能满足国际电信联盟电信标准部对光通信的最低要求。

The intensity fluctuation in space laser communication is analyzed quantitatively by using numerical simulation method, the relation of the intensity correlative scale with the atmospheric coherence length is obtained. And the referenced factors of ascertaining optimum receiving aperture are discussed. The optimum receiving aperture is defined base on the ITU-T, and the relation of optimum receiving aperture with atmospheric coherent length is educed, the result shows that the optimum receiving aperture is greatly increasing as the atmospheric coherence distance decreasing. When focused laser beam is used in space laser communication, at the strong atmospheric turbulent effect, for example r0 about 4 cm, only the receiving aperture approaches 5 times diameter of Airy spot, the lowest ITU-T demand can be satisfied.