电磁空心光束在湍流大气中的斜程传输特性

利用扩展的Huygens-Fresnel原理以及维格纳分 布函数(WDF)的二阶矩理论,推导出电 磁空心光束(PCEHB)在非均匀湍流大气中传输的均方根空间扩展、均方根角扩展和M²因子的 解析式。并数值模拟和分析了天顶角、光束阶数、湍流内尺度、波长、束腰宽度、初始相干 长度和初始偏振度对光束质量的影响。研究结果表明,随着天顶角的减小和初始偏振度的增 加,PCEHB的相对均方根空间扩展、相对均方根角扩展和相对M 2因子越小,光束受湍流的影 响越小。且初始偏振度对相对M²因子的影响小于相对均方根空间扩展和均方根角扩展。M²因 子也随着天顶角的增加而增加,当天顶角大于1时对M²因子的影响迅速增加。研究还发现 , 相对M²因子随着光束阶数、湍流内尺寸、波长和束腰宽度的增加,相干长度的减小而减小 。相对M²因子受天顶角和束腰宽度的影响大于其他参数。

Propagation properties of electromagnetic hollow beam through the atmospheric tu rbulence along a slant path

Based on the extended Huygens-Fresnel principle and the definition of the second moment of Wigner distribution function (WDF),the analytical expressi on of the root-mean-square (rms) spatial width,rms angular width and M²-factor of partially coherent electromagnetic hollow beam (PCEHB) in inhomogeneous atmos pheric turbulence have been derived.And we simulated numerically and analyzed t he effects of zenith angles,beam orders,inner scale of the turbulence,wavelen gth,waist width,initial coherence length and initial degree of polarization on beam quality.The results show that with the decrease of zenith angles and the increase of initial degree of polarization,the rms spatial width,rms angular w idth and relative M²-factor of PCEHB become small,whi ch means the beam is less affected by turbulence.And the effect of initial degree of polarization on rela tive M²-factor is smaller than that of relative rms s patial width and relative r ms angular width.The M²-factor also increases with th e increase of zenith angle s,and the influence on M²-factor increases rapidly wh en the zenith angles is gr eater than 1.It is also found that the relative M²-fa ctor decreases with the in crease of beam order,inner scale of the turbulence,wavelength and waist width and the decrease of initial coherent length.And relative M²-factor is affected by zenith Angle and waist width more than other parameters.