Liquid-Core-Microtubule-Enhanced Laser Sensor for High-Resolution Temperature Measurement

We present a fiber laser temperature sensor based on temperature dependence whisper gallery mode-based microcavity. Three different thermo-optic coefficient liquids are injected into a thin-wall thickness microtubule for the different temperature sensitivity of whisper gallery mode shift. The sensor temperature sensitivity increases with the absolute value of the liquid core thermo-optic coefficient. The theoretical model of whisper gallery mode temperature response is analyzed. A liquid core microtubule is inserted into the erbium-doped fiber ring laser (FRL) cavity as the optical filter and sensing unit simultaneously, so the lasing wavelength can be used to detect the temperature change of the medium. Due to the narrow spectral width of the sensing laser, a high sensing resolution system is experimentally confirmed. With the combination of the liquid core to increase the sensitivity and FRL cavity to increase sensing resolution, the high sensitivity of 112.8 pm/°C of the sensing system is demonstrated and the thermal resolution is $8.16\times 10^{-{3}}\,\,^{\circ }\text{C}$ .