【作者】 李睿；

【导师】 谭中伟；

【作者基本信息】 北京交通大学 ， 光通信与移动通信， 2013， 硕士

【摘要】 近年来,光纤光栅已成为新型光器件领域的研究热点之一,它在光通信和光纤传感领域极具发展前景。波长解调技术是光纤光栅应用于传感系统的最关键环节,高精度低成本的快速波长解调方案将会在很大程度上推进光纤光栅传感系统的商业化进程。本文研究的目的是设计和验证一种无源的、大动态检测范围、高灵敏度、低成本的高性能新型滤波方案。文章以大型工程损伤的动态监测需求和波长检测中解调精度的基本概念为出发点,深入研究了几种相对具有速度优势的边缘滤波解调方案,在此基础上提出和验证了一种基于虚像相位阵列的锯齿波光谱滤波器,并在光纤光栅传感系统中实现了波长解调功能。本论文的主要工作如下：1)研究了光纤光栅在检测大型工程损伤中的低频动态响应特性、波长检测中解调精度对采样率的要求以及超高速波长检测基础的发展状况。研究了几种边缘滤波解调方案的工作原理并比较评价了其优缺点。强调了应用中对高速高精度低成本波长解调方案的迫切需求。2)研究了虚像相位阵列的光谱色散定律,利用其高分辨率特性设计了一种基于虚像相位阵列的周期性无源锯齿波光谱滤波器,并结合此种滤波器的性能特点探讨了其在光纤传感、密集波分系统的波长检测及产生高速锯齿波信号三个方面的应用前景。3)对锯齿波光谱滤波器进行了深入的理论分析,在此基础上建立了数据仿真模型,利用Matlab仿真软件由线性度、信噪比、占空比三个性能指标对锯齿波光谱滤波器的波长解调性能进行了仿真与优化,并考虑实际应用中因外界环境的微小扰动引起的光强掩膜板位置和入射角度的微小变化对系统性能的影响。研究对比了反射式和透射式工作方式下锯齿波滤波器的损耗情况,依据参数优化结果设计并搭建了透射式工作方式下的锯齿波光谱滤波器实验装置,完成实验获得了附加损耗小于6dB的锯齿波光谱滤波器,此滤波器具有周期为2.4nm、动态测量范围为30nm、占空比超过85%、的周期性锯齿形响应函数。4)利用经实验测试的锯齿波光谱滤波器作为波长解调设备,设计了光纤光栅传感系统实验,利用光谱仪测得的波长漂移与示波器测得的光功率变化相一致,验证了锯齿形光谱滤波器在传感系统中的波长解调功能。更多还原

【Abstract】 Fiber Bragg grating is one of a hotspot in the new optical component field recently, which has great development prospects in the field of optical communication and fiber sensing. Wavelength demodulation is the most important element in a FBG based fiber sensing system. Wavelength demodulation scheme which has high resolution and high demodulate speed will advance the process of commercialization of Fiber Bragg grating sensing system. This thesis aims at designing and an experimental proof of a passive, large dynamic range, high sensitivity, low cost and high performance of new demodulation scheme.Fast sensitive demodulation scheme is emerging in dynamic monitoring for structural health monitoring system and wavelength interrogation. Here we propose and demonstrate a sawtooth spectral filter based on Virtually Imaged Phased Array, and applied it to a FBG based fiber sensing system as a wavelength demodulator. The main works are as follows.1) Dynamic response of FBG sensor in low-frequency and demodulation precision of wavelength interrogation are studied. Working principle of several edge filters and comparison are analyzed.2) Spectral dispersion law for the VIPA is demonstrated. Proposed a passive periodic sawtooth spectral filter based on VIPA. Demonstrated its application to fast sensitive interrogation of concatenated multi-channel FBG sensors ultrahigh-frequency electrical sawtooth waveform generation and wavelength interrogation in DWDM communication system.3) Simulated the linearity, SNR, duty cycle with Matlab based on theory analysis of sawtooth spectral filter. Simulated the performance of the filter with micro shift of intensity mask and incident angle. Designed and Fabricated a Sawtooth spectral filter with optimized parameter. High-resolution periodic sawtooth-shaped spectrum is produced.4) A FBG based fiber sensing system with an experimental tested sawtooth spectral filter. Demonstrated the wavelength demodulation function of the Sawtooth spectral filter.更多还原