Fiber Ring Laser Temperature Sensor Based on Liquid-Filled Photonic Crystal Fiber

A temperature sensor based on a fiber ring laser embedded with liquid-filled photonic crystal fiber (PCF) is proposed and experimentally demonstrated. High refractive index liquid is infiltrated into an index-guiding PCF to generate band gap-like effect then used as the laser filter and the sensing head simultaneously. With the temperature increasing, the emission wavelength of the fiber laser shifts to the shorter wavelength and the output intensity increases due to the band gaps' movement. The temperature sensitivity -1.747 nm/degrees C and 0.137 dB/degrees C are obtained utilizing the wavelength modulation and the intensity modulation, respectively, with high signal-to-noise ratio ( 55 dB), narrow 3-dB bandwidth (less than 0.08 nm) and good stability.