中文摘要：

采用光纤部件的自由空间光通信系统需要把接收到的光束耦合进单模光纤中，然而由于大气湍流的影响，使光纤耦合效率下降。自适应光学能够减小大气湍流效应，提高光纤耦合效率，根据大气湍流参数的空间光到单模光纤耦合效率表达式，得到了自适应光学校正下单模光纤耦合效率表达式，仿真结果显示：自适应光学能够增加空间相干长度，从而有效提高光纤耦合效率。同时还研究了斯特列尔比与耦合效率的关系，结果表明：无论有无自适应光学校正，两者都具有很好的拟合关系，因此在实际中可以用比较简单的斯特列尔比近似估计耦合效率。

英文摘要：

The received laser beam in a free-space optical communication using fiber-optic components system must be coupled into a single-mode fiber. However, atmospheric turbulence degrades the fiber- coupling efficiency. Adaptive optics can reduce the effects of atmospheric turbulence and improve fiber coupling efficiency. According to space light into single-mode fiber coupling efficiency expression with the atmospheric turbulence parameters, the single-mode fiber coupling efficiency expressions based on adaptive optics correction was deduced. Simulation results show that adaptive optics system correcting the aberrations induced by turbulence can increase the spatial coherence radius and then can improve the coupling efficiency. The the relationship between Strehl ratio and coupling efficiency was studied. The results show that regardless of the presence or absence of adaptive optics correction, both have good fitting relationship. Therefore, simple Strehl ratio can be used to estimate the single-mode fiber coupling efficiency.