High-resolution broadband phase interrogation for fiber optic interferometer using frequency stabilization and PGC demodulation

We proposed an high-resolution broadband phase interrogation technique for an interferometric fiber optic sensor which is designed as an unbalance michelson interference structure. The frequency stabilization technique based on PoundDrever-Hall (PDH) method is used for reducing low-frequency phase noise of the laser. An (Piezoelectric Transition) PZT, acting on one arm of the interferometer, is used to generate additional phase modulation. A phase generation carrier (PGC) algorithm is proposed for phase demodulation. The experiment results show that the proposed system has a very wide wavelength detection capability (from 0.1 Hz to 500 Hz) with an ultrahigh resolution of 2 × 10^-4 rad@0.1 Hz, and better than 10^-5 rad in the frequency range from 1 Hz - 500 Hz.