High Sensitivity Fiber Optic Temperature Sensor Based on Tunable Laser Vernier Sampling

Abstract

A high-sensitivity optical fiber temperature sensor based on the vernier sampling of tunable laser was proposed. The sensor contains only one fiber Sagnac interferometer (FSI), and the Vernier effect is achieved by controlling the sampling interval of the tunable narrow-band laser. When the wavelength sampling interval of the tunable laser is close but not equal to the free spectral range (FSR) of the FSI, the spectrum received by the optical power meter will be the envelope generated by the Vernier effect. The experimental results show that for the FSI with an FSR of 2.47 nm, when the sampling interval of 2.78 nm, which is slightly greater than the FSR of the FSI, is selected, an interference spectrum envelope is obtained, and its temperature sensitivity is about 9.1 times that of the FSI. The results prove that vernier sampling is feasible to improve the sensitivity of a single FSI, and its advantage is that the sampling interval can be flexibly controlled to achieve different sensitivity magnifications.