Fabry–Perot Cavity on Demand for Hysteresis Free Interferometric Sensors

We propose a dual air cavity based Fabry-Perot interferometer for the sensing of physical parameters such as strain and curvature. This highly stable and compact structure can be fabricated by splicing SMF with hollow core photonic crystal fiber (HCPCF) with optimized splicing parameters. The proposed structure showed negligibly small hysteresis along with long range of operation. The interference pattern can easily be controlled by controlling the geometry of the cavities according to the requirement. Experimental results show that the proposed structure has a strain and curvature sensitivity of 4.08 pm/με, 2.23 nm/ m^-1. The temperature sensitivity varies from 0.5 to 9 pm/°C. Moreover, the solid silica region in the probe can be utilized to study the effect of refractive index of surrounding medium.