部分相干光在大气湍流中水平传输路径上的展宽与漂移

Spreading and Wander of Partially Coherent Beam Propagating along a Horizontal-Path in the Atmospheric Turbulence

基于部分相干高斯谢尔模型(GSM)光束在强湍流中的光束扩展半径,利用Andrews和Philips经典漂移方差模型推导了部分相干光在中强弱大气湍流中水平传输的漂移方差表达式,讨论了部分相干光在中、强、弱大气湍流中的展宽和漂移特性。结果表明:部分相干光的光束扩展受湍流的影响比受完全相干光的影响要小,初始半径越小的光束受到湍流的影响越大。短距离传输时,不同波长引起的光束漂移差别很小,且随着初始光束半径的增大这种差别随之减小。传输距离大于2km时,中强湍流中光束漂移均与波长有关且强湍流区漂移量较为明显。传输距离在10km内,光束空间相干长度大于0.005m时,光源空间相干长度对漂移的影响很小。

Based on the formula of beam width of Gaussian-Schell model beam in strong turbulence, the expression of wander variance for a horizontal-path propagating partially coherent beam in the atmospheric turbulence is derived using the general expressions of the beam wander variance models of Andrews and Philips, and the spreading and wander of a partially coherent beam through the whole atmospheric turbulence are discussed. The results show that the partially coherent beam is less affected by turbulence than the fully coherent beam. The smaller the initial beam radius of partially coherent beam is, the more seriously the beam may be affected by turbulence. Within the short propagation distance, the beam wander caused by different wavelengths has little difference, which can reduce as the initial beam radius increases. When the propagation distance is further than 2 km, beam wander in both strong and weak turbulences is related to the wavelength, which is more obvious in strong turbulence. When the spatial coherence length is greater than 0. 005 m, it has little effect on the beam wander in propagation distance of 10 km.