Single-mode fiber-optic Fabry–Perot interferometry sensor based on optical cross-correlation demodulation

Abstract

A single-mode fiber-optic Fabry–Perot interferometry (FPI) sensor based on optical cross-correlation demodulation is presented, with advantages of both low cost and small size. The sensor mainly consists of a light-emitting diode, a glass wafer, a linear charge-coupled device, a cylindrical lens, a fiber-optic coupler, a sensing head, and a circuit board. The cavity length of the FPI sensor is demodulated by the optical cross-correlation relationship between the glass wafer and the Fabry–Perot cavity. When the cavity length changes, the pixel number corresponding to the peak value of the cross-correlation image shifts accordingly. To optimize the demodulation parameters, a simulation model is established. The experimental results show that the resolution and variation range of cavity length measurement are achieved to be 0.6 nm and ±4 μm, respectively. The proposed fiber-optic sensor is promising for the temperature and pressure measurements in circumstances of intense electromagnetic interference and long distance.