摘要1960年，伴随着激光诞生的还有人们对于激光通信技术的渴望。激光通信作为一种无线通信技术，由于其传输速率快，信息容量大等出色的优点,因而正在逐渐被越来越多的研究者开发完善。因为传输过程是裸露在大气中的，又因为大气是一个不稳定的环境，比如：大气湍流、大气吸收、大气散射等因素对激光传输造成不同程度的影响，这些影响直接导致了传输信号的质量下降。因此，想要克服大气对激光通信的影响，对于大气激光通信模拟信道仿真的研究是刻不容缓的。86105

本文主要的任务是：

（1）介绍了大气激光通信技术的发展史，还有国内外的研究现状，以及现今该技术所面临的难题。分析了大气激光通信技术的原理和技术。

（2）由于大气湍流不稳定，所以首先研究了随机场理论，主要分为均匀各项同性随机场和局部均匀各项同性随机场，结合这两个理论，可以得出较为准确的大气湍流变化规律。大气湍流对激光传输的影响还表现在相位和到达角会出现不同程度的起伏，经过公式计算得出大气湍流强度可以根据折射率结构函数在近地面处分为三种：强湍流，中湍流，弱湍流。

    （3）了解到大气衰减对激光通信的影响大，特别是大气吸收和大气散射。研究了关于大气透射率的曲线，大气透射率随着传输距离的增大而减小；波长不一样，大气在相同透射率的情况下传输距离也不一样；关于大气的损耗功率与传输距离的相关曲线。

毕业论文关键词：激光通信；大气衰减；大气吸收；大气湍流

Abstract  In 1960, with the development of the laser, laser communications technology were found。 Laser communication as a wireless communication technology, because of its fast transmission speed, large-capacity information and other outstanding advantages。 Thus it is gradually being more and more researchers have developed improved。 Because the transmission process is exposed to the atmosphere, but also because the atmosphere is an unstable environment, such as: atmospheric turbulence, atmospheric absorption and atmospheric scattering and other factors cause varying degrees of influence on the laser transmission, which led directly affect the quality of the transmission signal decline。 So, you want to overcome the effect of atmospheric laser communications, atmospheric laser communication channel analog simulation research is imperative。

The main task of this paper are:

  (1)describes the history of atmospheric laser communication technology, as well as the current research, as well as the current challenges facing the technology。 The principle technical and atmospheric laser communication technologies。

  (2) due to atmospheric turbulence is unstable, so first study the random field theory, it is pided into homogeneous isotropic random fields and locally homogeneous isotropic random field, the combination of these two theories, we can draw more accurate atmospheric turbulence law。 Effects of atmospheric turbulence on laser transmission is also reflected in the phase angle of arrival and will be varying degrees of ups and downs, through a formula calculated turbulence intensity according to the refractive index structure function in the near-surface disposal of three types: strong turbulence, turbulence, weak turbulence。

  (3)understand the atmospheric attenuation on laser communications, especially the atmospheric absorption and atmospheric scattering。 Research on atmospheric loss of power and transmission distance correlation curve; curve, atmospheric transmittance on atmospheric increases as the transmission distance decreases; not the same wavelength, the atmospheric transmission in the case of the same transmittance distance Different。