Fig. 1. Schematic diagram of phase shift fiber grating structure

Fig. 2. Flow diagram of PGC-SDD algorithm

Fig. 3. Flow diagram of PGC-DCM algorithm

Fig. 4. Flow diagram of PGC-Arctan algorithm

Fig. 5. J₁（C）J₂（C）curve graph varying with C

Fig. 6. J₁（C）/J₂（C）curve graph varying with C

Fig. 7. Log-amplitude spectrums of simulated demodulation with three algorithms

Fig. 8. DFB optical fiber hydrophone system based on Mach-Zehnder interference principle

Fig. 9. Linear amplitude spectrums tested by three algorithms