High-Sensitive Fiber Optic Temperature Sensor Based on Range-Extended Multiorder Interference Demodulation

A fiber optic temperature sensor with high sensitivity is proposed, utilizing range-extended multi(m)-order interference demodulation. The sensor features an ethanol-filled Fabry-Perot (FP) inline microcavity, offering a sensitivity of approximately -470 pm/°C. By determining the peak order through average amplitude and subsequently applying wavelength demodulation for precise temperature estimation, the sensor achieves an extended measurement range while maintaining high sensitivity, and this new approach overcomes limitations posed by potential spectral peak central wavelength overlap at different temperatures, thereby enabling temperature demodulation range from $- 20~^{\circ }$ C to $80~^{\circ }$ C. Notably, it demonstrates a rapid response time and the sensor’s robustness against bending interference. With its straightforward design and dependable performance, the sensor is well-suited for diverse applications, presenting a practical solution for high sensitivity, high precision, and wide-range temperature measurements.