拉盖尔-高斯波束在弱湍流海洋中轨道角动量传输特性变化

瑞托夫近似方法被用于分析研究弱湍流对海水环境中拉盖尔-高斯(Laguerre-Gaussian, LG)波束轨道角动量模式探测概率、串音概率以及螺旋谱分布的影响.结果表明:海洋湍流对轨道角动量的影响明显强于大气湍流, 海水环境中LG波束信号轨道角动量模式有效传输距离只有几十米；海洋湍流明显导致信号轨道角动量模式探测概率下降, 轨道角动量模式串音变强, 螺旋谱严重扩展；海洋湍流的影响随着轨道角动量角向模式、径向模式增加, 以及发射波长减小而增强.虽然较长的波长能降低海洋湍流影响, 但考虑到海水的散射和吸收作用, 蓝绿波长仍然是最佳选择.

Changes of propagation properties of orbital angular momentum for Laguerre-Gaussian beams in weak turbulent ocean

Rytov approximation is used to analyze the turbulence effects on the detection probability, crosstalk probability and spiral spectrum of the orbital angular momentum (OAM) for Laguerre-Gaussian (LG) beams in weak oceanic turbulence. Numerical results indicate that the oceanic turbulence has much stronger effect on the OAM modes than atmospheric turbulence, and the effective range of the signal OAM mode of LG beams is limited only to several decametres in turbulent ocean. Oceanic turbulence induces signal OAM modes detection probability decrease, mode crosstalk, and spiral spectrum spread badly. The effects of oceanic turbulence increase with the increase of OAM angular modes, radial modes, beam width, and the decrease of the wavelength. Longer wavelength can effectively mitigate oceanic turbulence effects. However, blue and green wavelengths are preferred due to the absorption and scattering effects of the oceanic water.