High-Stability PGC Demodulation Algorithm Based On a Reference Fiber-Optic Interferometer With Insensitivity to Phase Modulation Depth

Abstract

An ameliorated phase generated carrier demodulation algorithm based on a reference interferometer is proposed. It is theoretically analyzed, numerically simulated, and experimentally verified in this paper. The method of matching the amplitude of the quadrature signal in the reference interferometer algorithm eliminates the harmonic distortion caused by modulation depth fluctuations, suppresses system noise, and improves system stability. In experiments, where the sensed signal amplitude is 0.68 rad, the frequency is 1 kHz, and the modulation depth ranges from 1.5 to 3.5 rad, the ameliorated algorithm has SINAD that reaches 24.5 dB, which is an average improvement of 7.9 dB over the PGC-DCM algorithm based on a reference interferometer and an average improvement of 3 dB over the PGC-Arctan algorithm based on a reference interferometer. The ameliorated algorithm achieves a THD of 0.451%, which consistently maintains the best level of the traditional PGC algorithm based on a reference interferometer. The method provides an effective reference for signal processing in practical applications of fiber-optic sensors.