采用3×3耦合器的分布反馈式光纤激光传感器解调技术  

Demodulation Technology of Distributed Feedback Fiber Laser Sensor Based on 3 × 3 Coupler

作　　者：毛欣[1] 黄俊斌[1] 顾宏灿[1] MAO Xin HUANG Jun-bin GU Hong-can(Department of Weaponry Engineering, Naval University of Technology, Wuhan 430000, Chin)

机构地区：[1]海军工程大学兵器工程系,湖北武汉430000

出　　处：《发光学报》2017年第3期395-401,共7页Chinese Journal of Luminescence

基　　金：粤港关键领域重点突破项目(2004A10403021);广东省攻关计划(2006A10401006)资助项目~~

摘　　要：为了实现分布反馈式光纤激光传感器(DFB FL)大动态范围、稳定解调,建立了基于3×3耦合器的迈克尔逊干涉仪解调系统。对该系统所采用的对称解调算法(NPS)和反正切解调算法进行了深入研究。首先,介绍了基于3×3耦合器解调算法的原理及耦合器不对称时的调校方法。接着,对干涉仪所需最小非平衡路径长度的选取与系统强度噪声、激光器频率噪声的关系进行了分析。最后,针对NPS算法与反正切算法最大可解调信号幅度进行了分析对比,并研究了微分器对对称解调方法解调范围的影响。实验结果表明:NPS算法动态范围高于反正切算法,微分器的幅频特性不理想会减小解调动态范围。在采样频率为125 k Hz、信号频率为1 k Hz、干涉仪非平衡路径为100 m时,NPS算法与反正切算法的动态范围分别达到96 d B和90 d B。用解调前调校的方法,基于3×3耦合的解调方法动态范围大,能够实现稳定解调,满足工程应用要求。The 3 × 3 coupler-based Michelson interference demodulation system was established to achieve a stable demodulation of distributed feedback optical fiber laser sensor （ DFB FL） in a wide dynamic range. The symmetric demodulation algorithm （NPS） and arctangent demodulation algorithm used in this system were in-depth researched. Firstly, the theory of the 3× 3 coupler-based demodula- tion algorithm and calibration method used in asymmetry coupler were presented. Secondly, the selec- tion of minimum unbalanced interferometer path length, as well as the relation of system noise and fre- quency noise of laser were analyzed. Next, the amplitude of the maximum demodulated signal of NPS and the arctangent algorithm were compared. At last, the effect of differentiator on the dynamic range of NPS method was analyzed. The experiment results show that the dynamic range of NPS method is wider than that of arctangent algorithm, and a bad amplitude-frequency characteristic of differentiator will narrow the dynamic range of demodulation. The dynamic range of NPS algorithm and arctangent algorithm reaches to 96 dB and 91 dB respectively when the sampling frequency is 125 kHz, signal frequency is 1 kHz, and interferometer＇s unbalanced length is 100 m. By applying calibration before demodulation, the 3×3 coupler-based demodulation methods may produce a large dynamic range,which can achieve a stable demodulation and meet the requirements of engineering application.

关 键 词：分布反馈式光纤激光传感器 3×3耦合器 被动零差解调 

分 类 号：TN253[电子电信—物理电子学] TP212.14[自动化与计算机技术—检测技术与自动化装置]