部分相干电磁光束在湍流大气中传输的交叉偏振度

Degree of Cross-Polarization of Partially Coherent Electromagnetic Beams Propagating in Turbulent Atmosphere

推导部分相干电磁高斯-谢尔模型光束在湍流大气中的交叉谱密度矩阵.根据交叉偏振度的理论,研究部分相干电磁光束在湍流大气中的交叉偏振度的变化情况.研究表明,部分相干电磁光束的交叉偏振度由大气折射率结构常数、光源相关长度、光束初始偏振度和观察点位置决定.交叉偏振度不同于一般偏振度,它的值不再仅仅局限在0～1,而是可以取任何非负值.同时也发现,与一般偏振度的分布趋势截然不同,交叉偏振度在湍流大气中会呈先扩散,后压缩的分布趋势.同时,当相关长度取值相等时,部分相干电磁光束在湍流大气中传输的交叉偏振度不再发生变化.

The cross-spectral density matrix of partially coherent Gaussian-Schell model electromagnetic beams propagating in atmospheric turbulence is derived.Based on the theory of degree of cross-polarization,the behaviour of partially coherent electromagnetic beams propagating through the atmospheric turbulence is investigated.It is shown that the degree of cross-polarization depends on the refraction index structure constant of turbulence,the correlation length of the source,the initial degree of polarization and the observation point.The degree of polarization is different from the usual degree of polarization which is restricted to the range 0~1,it may take on any nonnegative values.It is also found,the distribution of degree of cross-polarization is different from the usual degree of polarization,presents the trend of first diffuse then shrink.And,when the correlation length of the source takes same values,the degree of cross-polarization which the beams propagate in atmospheric turbulence will keep invariant value.