Sensitivity-enhanced all-fiber displacement sensor based on Lyot filter

An all-fiber optic high-sensitivity displacement sensor based on 45°-spliced PM Lyot filter is proposed and its sensing performance is investigated experimentally. According to the relationships between the dips and the displacements, the sensor has a good linearity in passive mode, whose R square is larger than 0.998, and the highest sensitivity of 132.55 pm/μm is obtained in the range of 200 μm displacement variation. Moreover, it can be compatible to an intracavity displacement sensing system, achieving narrow linewidth, high signal-to-noise ratio (SNR), and high resolution. It can be found that the sensitivity of the intracavity displacement sensor can be 60 pm/μm when the PMF fiber length is about 20 cm with a linewidth narrower than 0.05 nm and a SNR higher than 55 dB.