光通信系统中的激光准直与耦合技术研究

发布时间：2018-04-21 15:35

本文选题：光子晶体 + 表面波　；参考：《电子科技大学》2014年硕士论文

【摘要】：自由空间光通信是指以激光作为信息载体,在大气中传输信息的通信系统。光通信以其周期短、成本低、抗电磁能力强、保密性好等优点而被人们广泛关注。本文针对光通信系统中的激光准直与耦合技术进行研究,利用光子晶体对激光发散角进行准直,通过光学软件仿真对所得到的准直结果进行验证;设计出超宽带色散平坦的光子晶体光纤以提高光通信系统中的光传输效率,对光子晶体光纤和单模光纤的耦合特性进行研究分析。光子晶体是一种人工制造的光子带隙材料,这是由于介电常数周期性改变使得光产生折射性的周期性分布。光子禁带的产生使得有关光子晶体的许多应用都是依赖于其禁带的频率范围,这为光控制提供了一种新的机理,受到人们的广泛关注。本论文所做的主要工作包括:1.简述光通信原理以及激光准直与耦合的几种方法,确定文章采用光子晶体材料进行研究,并简述光子晶体的发展历程及其在光通信中的应用。介绍光子晶体的理论研究中主要的方法——平面波展开法、传输矩阵法及时域有限差分法,以及用光学软件对光子晶体仿真所用到的有限元法。2.利用表面波作用对传统二维光子晶体结构进行改进,考察激光束的准直效果。与传统的二维光子晶体结构对比发现具有表面结构的光子晶体取得较好的准直角,并且利用远场传输分布特性直观的分析准直效果。表面结构的色散曲线及二维光子晶体的能带曲线图通过平面波展开法计算求出。通过计算得出表面模式的准直波频率不在光子禁带范围内,并且利用软件对准直结果进行仿真,结果可以明确的看出具有表面结构的新型光子晶体准直效果优于传统的光子晶体准直。3.设计超平坦色散的光子晶体光纤,减小光在光纤中传输时的码间串扰。分析影响色散曲线的主要因素,得出的结论是包层空气孔半径和孔间距对色散产生了较大影响,对影响色散曲线的结构参数进行改变,优化光子晶体光纤的色散曲线,得出了大波长范围内的色散平坦曲线。分析影响光子晶体光纤与单模光纤耦合的因素,并将文中设计的超平坦色散光子晶体光纤与单模进行耦合,计算耦合损耗。
[Abstract]:Free space optical communication is a communication system which uses laser as information carrier and transmits information in atmosphere. Optical communication is widely concerned because of its short period, low cost, strong electromagnetic resistance and good confidentiality. In this paper, the laser collimation and coupling technology in optical communication system are studied, the laser divergence angle is collimated by photonic crystal, and the collimation result is verified by optical software simulation. The photonic crystal fiber with UWB dispersion flat is designed to improve the optical transmission efficiency in optical communication system. The coupling characteristics of photonic crystal fiber and single-mode fiber are studied and analyzed. Photonic crystal is a kind of artificial photonic bandgap material, which is caused by periodic change of dielectric constant to produce periodic distribution of light refraction. The generation of photonic bandgap makes many applications of photonic crystals depend on the frequency range of photonic crystals, which provides a new mechanism for optical control. The main work of this paper includes 1: 1. This paper introduces the principle of optical communication and several methods of laser collimation and coupling. It is determined that the photonic crystal material is used to study it. The development of photonic crystal and its application in optical communication are also briefly described. The main theoretical methods of photonic crystal are plane wave expansion method, transfer matrix method and finite-difference time-domain method, and the finite element method .2which is used to simulate photonic crystal with optical software. The conventional two-dimensional photonic crystal structure is improved by surface wave interaction to investigate the collimation effect of laser beam. Compared with the traditional two-dimensional photonic crystal structure, it is found that the photonic crystal with surface structure has a good quasi-right angle, and the collimation effect is analyzed intuitively by using the far-field transmission distribution characteristics. The dispersion curve of surface structure and the energy band curve of two-dimensional photonic crystal are calculated by plane wave expansion method. It is found that the collimation frequency of the surface mode is not within the range of photonic band gap, and the collimation results are simulated by software. The results show that the collimation effect of new photonic crystal with surface structure is better than that of traditional photonic crystal collimation. A photonic crystal fiber with ultra-flat dispersion is designed to reduce the intersymbol crosstalk when light is transmitted in the fiber. The main factors affecting dispersion curves are analyzed. The conclusion is that the radius of air holes and the spacing of holes in cladding have a great influence on dispersion. The structure parameters affecting dispersion curves are changed and the dispersion curves of photonic crystal fibers are optimized. The dispersion flatness curves in a wide wavelength range are obtained. The factors influencing the coupling between photonic crystal fiber and single-mode fiber are analyzed. The ultra-flat dispersive photonic crystal fiber is coupled with single mode and the coupling loss is calculated.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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