斜程湍流大气中矢量涡旋光束的OAM特性研究

基于螺旋谱理论推导出矢量涡旋光束在斜程大气湍流传输中的轨道角动量(orbital angularmomentum,OAM)谱,讨论了修正Kolmogorov大气湍流对不同阶矢量涡旋光束光场分布及光束OAM谱的影响。利用旋转毛玻璃作为随机相位屏,实验采集了矢量涡旋光束通过旋转毛玻璃后的光强图像与归一化强度。结果表明:经大气湍流斜程传输后,矢量涡旋光束的光强分布产生畸变且OAM谱发生弥散,OAM谱弥散程度随传输距离的增大而增大。传输距离不变时,天顶角越大,主OAM模相对功率越小,湍流内尺度减小与折射率结构常数增大均会导致主OAM模相对功率减小。同一传输路径下,随着湍流强度的增大,矢量涡旋光束中心相位奇点的强度逐渐增大,并且拓扑荷不变时,偏振阶数高的矢量涡旋光束受到的湍流影响较小。

Orbital angular momentum characteristics of vectorvortex beam in slant turbulent atmosphere

The orbital angular momentum (OAM)spectrum of vector vortex beam propagating in slant atmospheric turbulence is derived based on the spiral spectrum theory,and the influence of modified Kolmogorov atmospheric turbulence on the optical field distribution and OAM spectrum of vector vortex beams with different orders is discussed.Using a rotating ground glass as a random phase screen,the optical intensity image and normalized intensity of the vector vortex beam passing through the rotating ground glass are collected experimentally.The results show that the intensity distribution of vector vortex beam is distorted and the OAM spectrum is dispersed after the slant propagation of atmospheric turbulence,and the dispersion degree of OAM spectrum increases with the increase of propagation distance.At a constant transmission distance,the larger the zenith angle,the smaller the relative power of the main OAM mode.The decrease of the turbulence internal scale,and the increase of the refractive index structure constant both lead to a decrease of the relative power of the main OAM mode.Under the same propagation path,with the increase of turbulence intensity,the intensity of the central phase singularity of the vector vortex beam gradually increases,and the vector vortex beam with high polarization order suffers less from turbulence when the topological charge is constant.