【作者】 刘琦；

【导师】 杨元杰；

【作者基本信息】 电子科技大学 ， 导航制导与控制， 2018， 硕士

【摘要】 与普通高斯光束相比,涡旋光束具有很多特点,如光束中心光强为零、自身带有轨道角动量等。这种特点就使得涡旋光束在很多领域都拥有较高的应用价值,例如,光学捕获、光学旋转、非线性光学、生物医学、自由空间通信等。由于激光具有高强度、相干度和方向性等,当其应用在自由空间光通信技术时,具有容量大、体积质量小、抗电磁干扰性强等特点。在国防军事方面,需要拥有更高空间分辨率,时间分辨率,光谱分辨率等的航空航天侦查平台,未来的局部战争也需要具有更高抗电子干扰能力,通信能力,安全保密能力等的激光武器。这些系统都在大气信道中进行传输,其中面临的最大问题则是大气作用,为了提高系统的性能,必须要对激光大气传输进行深入的研究分析。则本文旨在研究反常涡旋光束在非柯尔莫戈洛夫大气湍流中的传输特性,主要内容如下:1.介绍了本文的研究动机和意义,并对光学涡旋的国内外研究发展概况以及光束在湍流大气中传输的国内外研究发展概况进行了总结分析。2.简要介绍了激光传输的基本理论和方法,归纳总结了几种常见的大气湍流功率谱模型和大气湍流的折射率结构常数模型,并介绍了光束质量的一些评价参数,包括光束传输因子,光束角扩展,斯特列尔比等。3.研究了新型反常涡旋光束在非柯尔莫哥洛夫大气湍流中的传输模型。首先对应用的基础理论和湍流模型进行理论介绍,并基于广义惠更斯-菲涅尔原理,结合非柯尔莫哥洛夫大气湍流的功率谱密度,推导出相关的交叉谱密度矩阵。随后应用相干与偏振统一理论,进一步研究了反常涡旋光束通过非柯尔莫哥洛夫大气湍流的光强分布、偏振度特性以及光谱相干度。进行数值模拟,探究不同的光束参数和湍流参数对光束光强、偏振度和相干度的影响。4.研究了新型反常涡旋光束通过非柯尔莫哥洛夫大气湍流后的光束质量。利用广义惠更斯-菲涅耳原理和维格纳的二阶矩定义,并结合非柯尔莫哥洛夫大气湍流的功率谱,对新型反常涡旋光束通过非柯尔莫哥洛夫大气湍流后的光束传输因子、方均根束宽、角扩展进行了理论推导。通过控制变量,进行数值模拟,分别探究光束传输因子、方均根束宽、角扩展在不同传输距离的情况下,随湍流指数项的变化情况,以及在不同光束参数项、不同湍流参数项下,随传输距离的变化情况,分析不同因素对光束质量的影响。更多还原

【Abstract】 Compared with the ordinary Gaussian beam,Vortex beam has many characteristics,such as the zero intensity of the center of the beam and the angular momentum of the orbit,etc.This characteristic makes vortex beams have high application value in many areas,for example,optical trapping,optical rotation,nonlinear optics,biomedicine,free space communication and so on.Because of its high intensity,coherence and directivity,the laser has the characteristics of large capacity,small volume and strong electromagnetic interference when applied to free space optical communication technology.In the military,but also has very important significance for laser atmospheric propagation,now the aerospace reconnaissance platform,needs to have higher spatial resolution,high temporal resolution,high spectral resolution.The future local wars also need laser weapons with higher ability to resist electronic jamming,communication capability,security and confidentiality.These systems are all transmitted in the atmosphere channel,and the biggest problem is atmospheric action.In order to improve the performance of the system,it is necessary to study and analyze the laser atmospheric transmission in depth.In this paper,we study the propagation properties of the anomalous vortex beams in the non-Kolmogorov turbulence.The main contents of this paper are as follows:1.The motivation and significance of the research are introduced.The research and development of optical vortex at home and abroad as well as the research and development of beam propagation in turbulent atmosphere at home and abroad are summarized and analyzed.2.This paper briefly introduces the basic theory and method of laser transmission,and summarizes several common refractive power spectrum of atmospheric turbulence model and atmospheric turbulence structure constant model,and introduces some evaluation parameters including beam quality,beam propagation factor,beam angle,Strehl ratio etc.3.Study of the transmission model of the anomalous vortex beams in the non-Kolmogorov turbulence.Firstly,the theory introduces the basic theory and application of the turbulence model,and based on the generalized Huygens-Fresnel principle,combined with the power of non-Kolmogorov turbulence spectral density,cross spectral density matrix is derived to push related.Then the application of unified theory of coherence and polarization,further study of the anomalous vortex beams through the non-Kolmogorov turbulence intensity distribution,degree of polarization characteristics and the spectral degree of coherence.The effects of different beam parameters and turbulence parameters on the intensity,degree of polarization and the spectral degree of coherence of the beam are investigated by numerical simulation.4.Study on the beam quality after the anomalous vortex beams through non-Kolmogorov turbulence.Firstly,the paper introduced the theory of beam quality,Based on the extended Huygens-Fresnel principle and the second-order moments of the Wigner distribution function,combined with the power of non-Kolmogorov turbulence spectrum,then the anomalous vortex beam propagation factor,the RMS beam width and the angular spread are deduced.Through numerical simulation,the control variables,respectively explore the beam propagation factor,RMS beam width,the angular spread in different transmission distance,changes with the index of turbulence,as well as in different beam parameters,different turbulence parameters,with the variation of the transmission distance,and analyze the changes of beam quality.更多还原