A Research Of Optic Fiber Interferometer Sensor Phase Hybrid Control Demodulation Scheme

This paper had completed a research about the demodulation algorithm of fiber optic interferometer sensor with hybrid control structure.Fiber optic interferometer sensor is a kind of phase modulated sensor which transfers the measure of environment physical quantities into interferometer light phase variation.Compared with the traditional electrical sensors,optical fiber sensor is applied more widely in space,aviation and navigation for its advantages,such as high sensitivity and large dynamic range.For improving the stability of phase generated carrier demodulation scheme,this paper added close loop control structure on the demodulation system and introduced feedforward control to the feedback control system in order to broaden the system bandwidth.Thus this paper proposed the hybrid control demodulation system for fiber optic interferometer sensor based on PGC.Firstly,this paper introduced the development of optical fiber sensor and some classic phase demodulation schemes and illustrated the principles of Mach-Zehnder optical fiber interferometer and the PGC demodulation algorithm.Besides it also compared the difference between the PGC-DCM and PGC-Arctan demodulation.This paper built a hybrid control demodulation system based on Mach-Zehnder interferometer by combining PGC-DCM demodulation algorithm and close-loop control technique for the purpose of defending modulation depth drift influence.Then,models of the sensing system parts had been built based on Simulink in the paper.After the controller parameters had been adjusted,the time domain analysis and frequency domain analysis had been done in this paper.Finally,the simulation experiment certified the closed-loop system owing higher stability under the situation where modulation depth drifted.On the other hand,the compare of the single close-loop and hybrid control demodulation system simulation proved that hybrid control system has wider measure bandwidth.The simulation verified the theoretical conjecture of this subject and show the advantages and feasibility of the demodulation scheme proposed in this paper.