拉盖尔-高斯光束的部分相干特性对克尔效应的影响  

Influence of Partially Coherence Properties on Kerr Effect of Laguerre-Gaussian Beams

作　　者：黄伟业 汪玉琴 张蓉竹[1] Huang Weiye;Wang Yuqin;Zhang Rongzhu(College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,Sichuan,China)

机构地区：[1]四川大学电子信息学院,四川成都610065摘要拉盖尔-高斯光束由于其特有的涡旋特性使其在大气传输过程中具有更好的稳

出　　处：《光学学报》2023年第20期256-262,共7页Acta Optica Sinica

基　　金：四川省科技厅科学基金(2021YFH0119);四川省重大科技专项(2019ZDZX0038)。

摘　　要：拉盖尔-高斯光束由于其特有的涡旋特性使其在大气传输过程中具有更好的稳定性。实际激光输出存在的部分相干性将对光束传输具有明显的影响,在大功率输出模式下,克尔效应的产生也会影响到光束传输的特性。本文从部分相干拉盖尔-高斯光束的交叉谱密度方程出发,推导了克尔效应作用下光束的传输表达式,利用分步傅里叶变换,对高功率部分相干涡旋传输中的克尔效应过程进行了模拟,并对比了不同参数影响下,光束相干性不同时克尔效应的差异。结果表明,克尔效应有助于维持光强的环状结构,提高拓扑荷数能够有效地缓解因相干度降低而造成的涡旋结构衰退的现象。Objective Laguerre-Gaussian beams have better stability in atmospheric propagation due to their unique vortex characteristics.However,the coherence of the transmitted beams will be significantly reduced under the influence of turbulent media.Furthermore,the generation of the Kerr effect can also affect the light transmission characteristics with high power output.We simulate the Kerr effect in the propagation of high-power partially coherent vortex beam and compare the influence of the Kerr effect with different coherence lengths and topological charges.The results indicate that the Kerr effect can help maintain the ring structure of light intensity,and increasing the topological charge can effectively alleviate the decay of vortex structures caused by the coherence decrease.Methods During analyzing the influence of the partial coherence of laser beams,the coherent mode decomposition method is adopted because the phase change cannot be directly added to the cross-spectral density function of the partially coherent beams.The modal expansion of the cross-spectral density of Gaussian Schell-model beams can be regarded as the incoherent superposition of a set of coherent sources,which is characterized by a Laguerre polynomial.Then,phase modulation is loaded onto the coherent light of each mode.When Kerr phase modulation is applied to coherent light,the split-step Fourier method can be employed to solve the problem.The main idea is to evenly divide the light transmission path into segments,with each segment considering linear and nonlinear effects.The influence of the Kerr effect on light wave transmission can be calculated by a model similar to a multi-layer phase screen.In calculation,linear transmission should be separated from nonlinear effects.Firstly,the diffraction effect of linear transmission at each distance,and the nonlinear effect on corresponding transmission distance need to be considered.The phase modulation caused by the Kerr effect is superimposed on the amplitude within the distance.The cross-spectra

关 键 词：物理光学 拉盖尔-高斯光束 部分相干 克尔效应 环状结构 

分 类 号：P427.1[天文地球—大气科学及气象学] O436.1[机械工程—光学工程]