Composite Multi-Parameter Sensor Based on Misaligned Peanut-Shaped Structure for Measuring Strain and Temperature

A composite fiber optic sensor based on a misaligned peanut-shaped structure and the single-mode fiber–multimode fiber–single-mode fiber (SMS) structure is proposed for simultaneous strain and temperature measurements. The misaligned peanut-shaped structure is formed by introducing a certain core-offset during fusion splicing. Through a simulation analysis of the sensor, the optical field distribution of the sensor structure under different offset amounts is obtained. The experimental results demonstrate that the sensor achieves a maximum strain sensitivity of −48.21 pm/µε with an offset of 35.61 µm under a strain range of 0–600 µε and a maximum temperature sensitivity of 124.29 pm/°C at a 24.35 µm offset with a temperature range of 35–95 °C. Meanwhile, the sensor with a 35.61 µm offset has two resonance peaks that are selected for simultaneous measurements, with strain sensitivities of −48.21 pm/µε and −47.04 pm/µε and temperature sensitivities of 75.71 pm/°C and 84.29 pm/°C, respectively. Therefore, the simultaneous measurement of the strain and temperature can be achieved through a matrix method, demonstrating that the sensor possesses a dual-parameter sensing capability for the strain and temperature.