High-Sensitivity Fiber Optic Temperature Sensor Based on Enhanced Vernier Effect

The accurate detection of temperature is crucial in industry, agriculture, military, and so on. This work implements a temperature sensor based on the enhanced Vernier effect principle, which is comprised of a Fabry–Perot interferometer and a fiber optic Sagnac interferometer with slightly detuned free spectral ranges (FSRs). The increase in sensitivity to temperature is due to the shift of their wavelength in the opposite direction with temperature. Compared to conventional Vernier effect-based temperature sensors, this sensor achieves highly sensitive temperature measurements without the need for a complex fabrication process or the configuration of a temperature-insensitive interferometer for reference. It was concluded that the ultrahigh sensitivity of the detection device was 61.11 nm/°C in the detection interval from 30.4 °C to 34 °C, and it also had a high linear response and longtime stability.