Fiber Bragg grating resonator for ultrahigh-resolution temperature sensing based on efficient cavity length

This paper proposed a novel ultrahigh-resolution optic fiber temperature sensing technique. The free spectral range of a fiber Bragg grating resonator is experimentally calibrated for temperature measuring with a narrow linewidth tunable fiber laser. The results show that this method has a high temperature sensitivity and can effectively eliminate the influence of the frequency instability of the laser source. A temperature resolution of 0.11 mK with good long term stability is demonstrated.