【作者】 尹红伟；

【导师】 谭吉春； 常胜利；

【作者基本信息】 国防科学技术大学 ， 物理学， 2011， 博士

【摘要】 非视线紫外通信是近年来自由空间光通信的一个典型应用，其利用波长200~300nm之间的紫外光的“日盲”特性实现全天工作，利用大气粒子对光的散射实现非视线传输，是一种可非视线工作的光通信手段。论文研究非视线偏振紫外大气传输特性，目的是获得定量评估紫外通信信号强度和偏振的手段，并找出提高紫外通信性能的方法。主要研究成果如下：建立偏振散射模型。紫外通信的信号具有强度和偏振两个特征，而现有基于椭球坐标系的单次散射模型和基于Monte Carlo的多次散射模型不能计算偏振特征。论文把现有的非偏振散射模型扩展为偏振散射模型，可以定量计算散射信号的偏振，并可计算收发偏振设置对散射信号的影响。提出偏振紫外通信的概念和系统结构，并完成验证性实验。现有的紫外通信系统只能检测散射信号的强度，其通信速率大多在几K到几十Kbps之间，远低于理论预言的通信速率。通过同时检测散射信号的强度和偏振，可以使现有系统的通信速率得到成倍的提高，此即偏振紫外通信。偏振紫外通信系统的发射端为配有1个时间相关偏振器的光源，接收端为配有1个时间无关检偏器阵列的探测器阵列；光源发出光子，通过起偏器而实现偏振编码，接着被大气粒子散射，然后被检偏器阵列检偏，最后根据探测器阵列上散射信号的分布特征实现偏振解码。初步实验证明2-偏振紫外通信是可行的。简化基于椭球坐标系的单次散射模型的计算过程；提出共面非偏振单次散射能量的经验公式。Elshimy提出的基于椭球坐标系的单次散射模型可以计算任意的收发几何设置，但其计算过程相当繁琐；论文大大简化了相关计算过程，降低了计算难度。所提出的共面非偏振单次散射能量的经验公式中，收发几何设置、大气参数和收发距离对于单次散射能量的影响非常直观，用于指导短距离紫外通信系统的设计更多还原

【Abstract】 Non-line-of-sight (NLOS) UV communication is an exciting application of free-space-optical (FSO) communication recently, it makes use of solar-blind UV as the communication wavelength to obtain all-day work, makes use of scattering of light by atmospheric particles to achieve NLOS propagation, and is an method of optical communication which can work at NLOS geometry. The main aims of this paper are to find a method that can measure the intensity and polarization of the signal of NLOS UV communication, and to find a way to enhance the performance of UV communication. The main conclusions are shown as follows:The polarized scattering models are set up. The signal of UV communication has two characteristics: intensity and polarization, but the existing scattering models, including the single-scatter models based on the spheroidal coordinate system and the multiple-scatter models based on Monte Carlo, can not calculate the polarization of the signal. By extending the existing unpolarized scattering models to polarized ones, the polarization of the scattering signal, and also the impact of the polarization setups on scattering signals, can be calculated quantitatively.The conception and the structure of polarized UV communication have been presented, and the elementary experiment have been done. The existing NLOS UV communication system can only measure the intensity of the signal, and the data rates are mostly among the range of several kilo bps to several tens of kilo bps, which are violently lower than the theoretically predicted data rates. By the means of measuring the intensity and polarization at the same time, the data rates of the existing systems can be greatly enhanced, this is the so-called polarized UV communication. The polarized UV communication system consists of a light source accompanied with a time-dependent polarizer and a detector array accompanied with a time-independent analyzer array; the polarizing information is coded by the polarizer, influenced by the atmospheric channel, analyzed by the analyzer array, and decoded according to the distribution characteristics of the scattering signals on the detector array. The decoding of the polarizing information for 2-polarization UV communication is validated by the experiment.The calculation process of the single-scatter model based on the prolate spheroidal coordinate system is simplified; the empirical formula of the single-scatter energies in the coplanar geometries is presented. The noncoplanar single-scatter model presented by Elshimy can solve arbitrary transmitter-receiver geometry, but the complicated calculation process may restrict its application; the calculation process is greatly simplified, thus the model is more tractable than before. In the empirical formula of coplanar unpolarized single-scatter energy, the impacts of the transmitter-receiver geometry, the atmospheric parameters, and the range to the single-scatter energy are very clear, this formula can be used for the design guidance of short-range UV communication system.更多还原