弯曲不敏感少模光纤研究

发布时间：2018-01-05 12:09

本文关键词：弯曲不敏感少模光纤研究　出处：《北京交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着光纤传输系统容量的迅速增加,模分复用技术成为当前提升光纤通信容量的研究热点之一。基于模分复用的少模光纤得到越来越多的关注,然而,当前对少模光纤中各阶模式的弯曲损耗及光纤弯曲性能优化问题的研究尚处空白。本文对少模光纤中高阶模的弯曲损耗进行了系统的理论研究。利用微扰法推导得到了各阶模式弯曲损耗的理论公式,可适用于研究多种光纤结构的高阶模式的弯曲损耗。本文研究内容主要涉及阶跃型和抛物线型下陷层辅助弯曲不敏感光纤,系统研究了LP01、LP11、LP21以及LP02四个标量模的弯曲损耗与模场直径。研究结果表明：光纤的芯层与下陷层之间的距离、下陷层的宽度、下陷层与包层的折射率差、涂覆层折射率、归一化频率以及纤芯半径(数值孔径)等结构参数对各阶模的弯曲损耗和模场直径均有影响。在相同曲率半径下,弯曲损耗随着模式阶数的增高而增大；芯层与下陷层之间的距离存在弯曲损耗优化点,较基模而言,高阶模式的弯曲损耗优化点要更接近芯层；对高阶模而言,涂覆层导致的弯曲损耗曲线周期性震荡的振幅和频率较基模要大；对于高阶模式模场直径的研究表明,下陷层的出现会减小各阶模式的模场直径,且模式阶数越高减小的幅度也越大；芯层与下陷层之间的距离的增加则能够增大各阶模式模场直径；在传输模式数量相同时,抛物线型光纤的弯曲性能要优于阶跃型光纤。本文的研究结果对于设计和制造弯曲不敏感少模光纤具有指导意义。
[Abstract]:With the rapid increase of optical fiber transmission system capacity, module division multiplexing technology has become one of the research hotspots in improving the capacity of optical fiber communication. Less mode optical fiber based on mode division multiplexing has received more and more attention, however. The research on bending loss of each order mode and optimization of bending performance of optical fiber is still blank. In this paper, the bending loss of high-order mode in low-mode fiber is systematically studied. The perturbation method is used to deduce the bending loss of high-order mode. The theoretical formula of bending loss of each order mode is obtained. It can be used to study the bending loss of high-order modes in various optical fiber structures. This paper mainly deals with step and parabola subsidence layer aided bending insensitive fibers, and systematically studies LP01 / LP11. The bending loss and mode field diameter of the four scalar modes of LP21 and LP02. The results show that the distance between the core layer and the subsidence layer, the width of the trapping layer, and the refractive index difference between the trapping layer and the cladding layer. The refractive index of coating layer, normalized frequency and core radius (numerical aperture) have effects on bending loss and mode field diameter of each order mode. The bending loss increases with the increase of mode order. The distance between the core layer and the subsidence layer has a bending loss optimization point, which is closer to the core layer than the base mode. For high-order modes, the amplitude and frequency of periodic oscillations caused by the coating layer are larger than those of the base mode. The study of the mode field diameters of higher order modes shows that the occurrence of the subsidence layer will reduce the mode field diameter of each order mode, and the higher the mode order is, the larger the amplitude will be. The increase of the distance between the core layer and the subsidence layer can increase the mode field diameter of each order. When the number of transmission modes is the same, the bending performance of parabolic fiber is better than that of step fiber.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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