Highly Sensitive Strain and Temperature Sensors Based on Vernier Effect in Cascaded Mach–Zehnder Interferometer and Sagnac Interferometer
Ruyue Shi, Hailiang Chen, Xiaoya Fan, Chaoyi Liu, Hongwei Li, Zhigang Gao, Sa Zhang, Mingqi Gu, Lida Li, Yu Zheng, Shuguang Li
Abstract
In this article, vernier effect (VE), which is an effective method to enhance the measurement sensitivity of strain and temperature, was experimentally studied through cascading a Mach-Zehnder interferometer (MZI) with a Sagnac interferometer (SI). The MZI consisted of a tapered single-mode fiber (SMF), while the SI was formed using a panda-shaped polarization-maintained fiber (PMF). Free spectral ranges (FSRs) of the two interferometers were slightly different from each other, and as a result, the VE was successfully excited. The experimental results demonstrated that the measurement sensitivity of strain was improved from 26.7 to −110.92 pm/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> at the temperature of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$24~^{\circ }$ </tex-math></inline-formula> C, while the measurement sensitivity of temperature was improved from −2978 to 7934 pm/°C at the strain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0~\varepsilon $ </tex-math></inline-formula>. The sensitivity was amplified about four times. The cross-sensitivity of temperature and strain measurements is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$71.53~\mu \varepsilon $ </tex-math></inline-formula>/°C. The proposed sensor exhibits in advantages of simple in construction, high sensitivity, and multiparameter measurements making it a superior contender for strain and temperature monitoring in engineering.