长周期光纤光栅的偏振相关损耗特性及其应用研究

发布时间：2018-09-11 19:42

【摘要】：长周期光纤光栅(LPFG)是一种用途很广的光纤光栅,由于其插入损耗小、带宽宽、后反射很小、对外界环境变化的反应灵敏度高、制作工艺简单、成本低等很多优点,受到国内外广大研究人员的关注,并且在近年来的技术发展当中,显示出了极为广阔的应用前景。随着研究的不断深入,人们对LPFG功能需求标准的不断提高,一些关于LPFG的新结构、新特性、新应用的研究已成为必然的发展趋势。本论文的工作内容围绕着长周期光纤光栅的偏振相关损耗(PDL)展开,主要包括两个方面,一是研究LPFG的PDL特性及其在扭转传感中的应用。二是讨论了相移长周期光纤光栅(PS-LPFG)和级联长周期光纤光栅(C-LPFG)的光谱特性和PDL特性。首先,阐述LPFG的耦合模理论和传输矩阵法。详细分析了LIFG的透射谱和模拟步骤,讨论了周期数和平均折射率调制对其透射谱的影响。从LPFG的传感模型出发,分析了LPFG扭转后的透射谱,并且对其偏振相关损耗的特性进行了实验研究和仿真,作出相应的理论分析对比。利用琼斯矩阵和传输矩阵法,理论分析和数值模拟LPFG扭转与PDL响应的关系,通过测量PDL幅值变化,可实现不受应变和温度干扰,对扭转传感的测量。此外,可以同时获得扭转方向和扭转角两个量,实验结果和数值模拟有较好的吻合,扭转灵敏度为2.7 dB/rad。理论分析和数值模拟了相移长周期光纤光栅的光谱特性,讨论了PS-LPFG长度、相移位置、相移大小对PS-LPFG的PDL峰值的影响。对比分析了级联长周期光纤光栅的传感特性。可以发现LPFG级联时,一个细微的谱移会对损耗谱的高精细度的条纹产生的很大的波动损失。并且讨论了物理参量对其的影响。
[Abstract]:Long-period fiber grating (LPFG) is a kind of fiber gratings with a wide range of applications, such as low insertion loss, wide bandwidth, small back reflection, high sensitivity to changes in external environment, simple fabrication process, low cost, and so on. It has attracted the attention of researchers at home and abroad, and has shown a very broad application prospect in recent years. With the deepening of the research, the standard of LPFG function requirements has been improved, and some new structure, new characteristics and new applications of LPFG have become an inevitable trend of development. The work of this thesis is focused on the polarization dependent loss (PDL) of long-period fiber gratings, including two aspects. One is to study the PDL characteristics of LPFG and its application in torsion sensing. Second, the spectral and PDL characteristics of phase-shifted long-period fiber gratings (PS-LPFG) and cascaded long-period fiber gratings (C-LPFG) are discussed. Firstly, the coupled mode theory and transmission matrix method of LPFG are introduced. The transmission spectrum and simulation steps of LIFG are analyzed in detail. The effects of period number and average refractive index modulation on the transmission spectrum are discussed. Based on the sensing model of LPFG, the transmission spectrum after torsion of LPFG is analyzed, and the characteristics of polarization dependent loss of LPFG are studied experimentally and simulated, and the corresponding theoretical analysis and comparison are made. The relationship between LPFG torsion and PDL response is analyzed and numerically simulated by Jones matrix and transfer matrix method. By measuring the amplitude of PDL, the torsion sensing can be measured without strain and temperature interference. In addition, the torsion direction and torsion angle can be obtained simultaneously. The experimental results are in good agreement with the numerical simulation. The torsional sensitivity is 2.7 dB/rad.. The spectral characteristics of phase-shifted long-period fiber gratings are theoretically analyzed and numerically simulated. The effects of PS-LPFG length, phase shift position and phase shift size on the PDL peak value of PS-LPFG are discussed. The sensing characteristics of cascaded long period fiber gratings are compared and analyzed. It can be found that a small spectral shift in the LPFG cascade results in a large fluctuation loss of the high fineness stripes of the loss spectrum. The influence of physical parameters on it is also discussed.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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