大气湍流对空间光耦合至单模光纤的影响

 根据弱湍理论，考虑湍流强度闪烁、孔径平均效应、湍流波前畸变及耦合系统跟踪误差的影响，导出了空间光到单模光纤的平均耦合效率及耦合功率起伏方差模型。根据Hufnagel-Valley 5/7折射率结构模型，对下行连接及上行连接的平均耦合效率及耦合功率起伏进行了研究。仿真结果表明，对于下行连接，随着地面接收天线孔径的增大，相对功率起伏先是由于孔径平均效应而减小，而后由于湍流波前畸变的影响而逐渐增大；对于上行连接，可忽略湍流波前畸变及孔径平均效应的影响。

Influence of atmospheric turbulence on coupling space light into single mode fiber

Based on weak turbulence theory,an average coupling efficiency model and a relative power fluctuations model are derived for coupling space light into single mode fiber in the presence of atmospheric turbulence.The effects of turbulence-induced wavefront distortion,scintillation,aperture averaging and residual tracking error of the angle-tracked coupling system are considered together.Using the Hufnagel-Valley 5/7 refractive-index structure model,average coupling efficiency and relative power fluctuations are investigated for both downlink and uplink.It is shown that for downlink,with the increase of receiver aperture,the relative power fluctuations first decrease due to the aperture averaging,and then increase due to the turbulence-induced wavefront distortion,and for uplink,the effects turbulence-induced wavefront distortion and aperture averaging can be ignored.