Fiber Mach-Zehnder Interferometer for Simultaneous Measurement of Strain and Temperature Based on Misaligned Peanut-Shape Structure

An all-fiber Mach-Zehnder interferometer(MZI) based on modal interference for simultaneous measurement of strain and temperature is proposed and demonstrated. One end of the sensing area is a single mode-multimode-single mode (SMS) splicing structure, and the other is a misaligned peanut-shape structure. This paper explored the influence of different misalignment amounts on the strain sensitivity of sensors. Experimental results have shown that misalignment can improve the strain sensitivity of the sensor, and within a limited range, the strain sensitivity increases with the increase of misalignment amount. The maximum misalignment amount of the sensors fabricated in this paper is 31.8 μm, and its maximum strain sensitivity in the range of
$0\sim 800\mu\varepsilon$
is -27.57
$\text{pm}/\mu\varepsilon$
. It was also used for temperature sensing experiments, and the maximum temperature sensitivity in the range of 30~90 °C is -173.57 pm/°C. By detecting the wavelength shifts of its two different interference dips with temperature and strain, the simultaneous measurement of strain and temperature can be realized.