All-digital Real Time Demodulation System of Fiber Laser Hydrophone Using PGC Method

After analyzing the sensing theory of a DFB fiber laser, the demodulation principle of fiber Bragg grating hydrophone using a phase generated carrier based on Michel son interferometer was introduced. A digital demodulation system based on DSP was designed then, and a feasible resolution was provided to the error-induced factor caused by the frequency error between that of sinusoidal modulation and of mixing signals. The experiment shows, the waveform of demodulated acoustic signal with low frequency was nice.