Highly sensitive fiber-optic temperature sensor based on Lyot filter cascaded with Fabry-Perot interferometer

A highly sensitive fiber-optic temperature sensor based on a Lyot filter cascaded with a Fabry-Perot interferometer (FPI) is proposed and demonstrated in this study. The FPI consists of a segment of hollow-core photonic crystal fiber (HCPCF) spliced between two single-mode fibers (SMFs), which is insensitive to temperature and strain and is an ideal reference interferometer. The Lyot filter is composed of two polarizers with an uiltra-fine polarization maintaining fiber (UFPMF) of a certain length for temperature sensing. By adjusting the length of the UFPMF, the free spectral range (FSR) of the Lyot filter is close to FPI, resulting in an optical Vernier effect and improved sensitivity. Experimental results show that with the Vernier effect, the temperature sensitivity is enhanced from -1.145 nm/& DEG;C to -59.31 nm/& DEG;C, and the sensitivity amplification factor is about 51.8. The proposed sensor with the Vernier effect has good performance in temperature sensing and is suitable for applications fields where high sensitivity temperature measurement is required.

Automated summary

A highly sensitive fiber-optic temperature sensor based on a Lyot filter cascaded with a Fabry-Perot interferometer (FPI) is proposed and demonstrated in this study. The FPI consists of a segment of hollow-core photonic crystal fiber (HCPCF) spliced between two single-mode fibers (SMFs), functioning as an ideal reference interferometer. By adjusting the length of the ultra-fine polarization maintaining fiber (UFPMF) in the Lyot filter, the optical Vernier effect is achieved and the temperature sensitivity is significantly enhanced. The proposed sensor shows good performance in temperature sensing and is suitable for applications requiring high sensitivity temperature measurement.