基于大调制中心频率的布里渊光相关域反射技术  

Brillouin Optical Correlation-Domain Reflectometry Based on Large Modulation Center Frequency

作　　者：江岳凯 路元刚[1] 姚雨果 张伍军 赫崇君[1] 梁璐璐 Jiang Yuekai;Lu Yuangang;Yao Yuguo;Zhang Wujun;He Chongjun;Liang Lulu(The Key Laboratory of Space Photoelectric Detection and Perception of Ministry of Industry and Information Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,Jiangsu,China;College of Electrical and Automation Engineering,Changshu Institute of Technology,Changshu 215506,Jiangsu,China)

机构地区：[1]南京航空航天大学空间光电探测与感知工信部重点实验室,江苏南京211106 [2]常熟理工学院电气与自动化工程学院,江苏常熟215506

出　　处：《中国激光》2023年第13期169-174,共6页Chinese Journal of Lasers

基　　金：国家自然科学基金(62175105,61875086);江苏省高等学校基础学科(自然科学)研究面上项目(21KJD510002)。

摘　　要：为了提高分布式光纤温度传感的空间分辨率,提出了一种基于大调制中心频率的外调制布里渊光相关域反射(BOCDR)新技术。笔者发现了外调制BOCDR系统中的拍频谱噪声,分析了该噪声的起因以及其对被测信号混叠的影响,并据此发现使用较大的调制中心频率可以抑制拍频谱噪声对布里渊散射信号混叠的影响,从而获得较高的空间分辨率及较大的温度测量范围。利用所提出的基于大调制中心频率的BOCDR新技术,在一个验证实验中,使用一段长为17.2 m的G657光纤实现了连续分布式测量。实验结果表明,外调制BOCDR系统的空间分辨率为11.6 cm,温度的测量不确定度为0.26℃,测量不确定度比同类系统低一个数量级。Objective Optical fiber sensors have a wide range of applications in aerospace,energy,electric power,transportation,and communications because of their advantage such as anti-electromagnetic interference,small size,and low weight.Traditional temperature sensing technologies based on fiber gratings,optical microcavities,Fabry-Perot interferometers,and Mach-Zehnder interferometers cannot achieve distributed measurements.Distributed fiber optic sensing technologies based on Raman scattering are incapable of achieving long-distance sensing.Therefore,a large amount of research has focused on Brillouin-scattering-based fiber sensing.Brillouin optical correlation-domain reflectometry(BOCDR)based on external modulation,can achieve distributed sensing with high spatial resolution and solve the problems of measuring spatial resolution fluctuations and laser sources that require highfrequency and large-amplitude modulation in BOCDR based on internal modulation.However,a spectrum aliasing problem in BOCDR based on external modulation affects the sensing system's spatial resolution.In this study,we report an external modulation BOCDR system with a large modulation center frequency to overcome signal noise aliasing and achieve temperature sensing with a high spatial resolution.Methods In this study,we first constructed a light source system for BOCDR based on external modulation,which consists of a function generator,a voltage-controlled oscillator,an electro-optic modulator,a laser source,an erbium-doped fiber amplifier,and an optical bandpass filter.During the measurement process,the Brillouin gain spectrum was obtained by continuously changing the modulation frequency,and the temperature information was demodulated from the measurement results.The different frequency components of the reference and Stokes light in the BOCDR system based on external modulation were compared(Fig.2),and the impact of beat spectrum noise was analyzed.The modulation center frequency influences the sensing system's spatial resolution and dynamic

关 键 词：光纤光学 光纤传感器 分布式传感 温度传感 布里渊光相关域反射 高空间分辨率 

分 类 号：TN247[电子电信—物理电子学]