Jiang Zejun, Wu Fugen, Yang Jun, Wen Kunhua, Xu Pengbai, Yu Zhangjun, Sun Jiangquan, Wang Yuncai, Qin Yuwen
Opt Express. 2022 Mar 14;30(6):9578-9589. doi: 10.1364/OE.454988.
A kind of hybrid fiber interferometer consisting of a fiber Sagnac interferometer (FSI), a closed-cavity Fabry-Perot interferometer (FPI), and an open-cavity FPI is proposed for generating combined-Vernier-effect. Through adjusting the polarization-maintaining fiber (PMF) length of the FSI, the free spectral range (FSR) is tailored to be similar to that of the parallel-connected reference FPI for producing the first Vernier effect, of which the spectrum is used to match the sensing FPI spectrum for obtaining the second Vernier effect. Noticeable lower and upper spectral envelopes are achieved in the first and second Vernier effects, respectively, so called the combined-Vernier spectrum. Accessibly, the upper envelope is only sensitive to the refractive index (RI) owing to the characteristics of the open-cavity FPI, while the lower one is immune to the RI and employed to detect the temperature by taking advantage of the FSI. Most importantly, the sensitivities of RI and temperature can be significantly improved simultaneously without crosstalk. The experimental results show that the RI sensitivity is -19844.67 nm/RIU and the temperature sensitivity is -46.14 nm/°C, which can be used for high-precision temperature and RI simultaneous measurement.
提出了一种由光纤萨格纳克干涉仪（FSI）、闭腔法布里 - 珀罗干涉仪（FPI）和开腔FPI组成的混合光纤干涉仪，用于产生组合游标效应。通过调整FSI的保偏光纤（PMF）长度，将自由光谱范围（FSR）调整为与并联参考FPI的自由光谱范围相似，以产生第一游标效应，其光谱用于与传感FPI光谱匹配以获得第二游标效应。在第一和第二游标效应中分别实现了明显的较低和较高光谱包络，即所谓的组合游标光谱。可以看出，由于开腔FPI的特性，较高光谱包络仅对折射率（RI）敏感，而较低光谱包络对RI不敏感，并利用FSI来检测温度。最重要的是，RI和温度的灵敏度可以同时显著提高且无串扰。实验结果表明，RI灵敏度为-19844.67 nm/RIU，温度灵敏度为-46.14 nm/°C，可用于高精度温度和RI的同时测量。
