Dual-Parameter Sensing of Parallel Fiber Sagnac Interferometer Based on Vernier Effect

A parallel-fiber-loop interferometer based on Vernier effect is proposed to detect strain and temperature. The interference generates between the outputs of two parallel fiber Sagnac interferometers (PSIs). Each SI is inserted into a polarization-maintaining fiber (PMF) with the same type but different length. The feasibility of the system is proven theoretically and experimentally. In the interference spectrum, it is observed that the sensor has clearer upper and lower limits than the cascade structure, which is more beneficial to track the drift of spectral envelope. Experimental results showed that the strain sensitivity increased from 8.13 pm/mu e for the single SI to 61.98 pm/mu epsilon for the PSIs. The temperature sensitivity increased from -1.51 nm/degrees C for the single SI to -14.32 nm/degrees C for the PSIs and the magnification is amplified eight times. The device has the advantages of simple structure, low cost, high sensitivity, and good stability, which has a good application prospect in strain and temperature measurement.

Automated summary

This paper proposes a parallel-fiber-loop interferometer based on Vernier effect for strain and temperature detection. The interference is generated between the outputs of two parallel fiber Sagnac interferometers. The feasibility of the system is proved theoretically and experimentally. The device has the advantages of simple structure, low cost, high sensitivity, and good stability, and has a promising application prospect in strain and temperature measurement.