An improved PGC demodulation algorithm for optical fiber interferometers with insensitive to carrier phase delay and modulation depth

Abstract

Phase generated carrier (PGC) demodulation is widely used in optical fiber interferometers due to its high sensitivity, large dynamic range and high signal fidelity. Based on the traditional PGC DCM demodulation scheme, we propose a algorithm to eliminate the carrier phase delay and compensate the modulation depth of PGC phase demodulation. The proposed algorithm provides real-time compensation for carrier phase delay and modulation depth without additional compensators. Through theoretical analysis and simulation, the performance of the improved demodulation scheme is compared with the traditional PGC-DCM demodulation algorithm. A complete demodulation system hardware is built, and the improved algorithm, the traditional PGC-DCM scheme and the traditional PGC-Arctan algorithm are tested respectively based on the Michelson interferometer. Experimental results show that the proposed algorithm is insensitive to carrier phase delay and modulation depth, its signal-to-noise ratio and distortion rate can reach 56.15 dB, and the total harmonic distortion rate is 0.13 %.