Temperature-insensitive fiber-optic refractive index sensor based on cascaded in-line interferometer and microwave photonics interrogation system  

作　　者：Xun Cai Yi Zhuang Tongtong Xie Shichen Zheng Hongyan Fu 

机构地区：[1]Xiamen University,Department of Electronic Engineering,Xiamen,China [2]Xiamen University,Fujian Key Laboratory of Ultrafast Laser Technology and Applications,Xiamen,China

出　　处：《Advanced Photonics Nexus》2024年第4期118-125,共8页先进光子学通讯（英文）

基　　金：supported by the National Natural Science Foundation of China(Grant No.61975167).

摘　　要：A compact and high-resolution fiber-optic refractive index(RI)sensor based on a microwave photonic filter(MPF)is proposed and experimentally validated.The sensing head utilizes a cascaded in-line interferometer fabricated by an input single-mode fiber(SMF)tapered fusion with no-core fiber-thin-core fiber(TCF)-SMF.The surrounding RI(SRI)can be demodulated by tracing the passband’s central frequency of the MPF,which is constructed by the cascaded in-line interferometer,electro-optic modulator,and a section of dispersion compensation fiber.The sensitivity of the sensor is tailorable through the use of different lengths of TCF.Experimental results reveal that with a 30 mm length of TCF,the sensor achieves a maximum theoretical sensitivity and resolution of-1.403 GHz∕refractive index unit eRIUT and 1.425×10^(-7) RIU,respectively,which is at least 6.3 times higher than what has been reported previously.Furthermore,the sensor exhibits temperature-insensitive characteristics within the range of 25℃-75℃,with a temperatureinduced frequency change of only±1.5 MHz.This value is significantly lower than the frequency change induced by changes in the SRI.The proposed MPF-based cascaded in-line interferometer RI sensor possesses benefits such as easy manufacture,low cost,high resolution,and temperature insensitivity.

关 键 词：fiber-optic sensor microwave photonics frequency demodulation Mach-Zehnder interferometer 

分 类 号：TN2[电子电信—物理电子学]