Distributed optical fiber sound wave sensing device based on homodyne detection and demodulation method

The invention discloses a distributed optical fiber sound wave sensing device based on homodyne detection and a demodulation method. The distributed optical fiber sound wave sensing device comprises a narrow linewidth laser, an optical fiber isolator, a semiconductor optical amplifier, an erbium-doped optical fiber amplifier I, an optical fiber circulator, a sensing optical fiber, an optical fiber coupler I, an optical fiber coupler II, a straight waveguide phase modulator, a first Faraday rotator mirror, a second Faraday rotator mirror, an erbium-doped optical fiber amplifier II, a photoelectric detector I, a photoelectric detector II, a data acquisition unit and a data processing unit. According to the invention, the optical fiber coupler I, the photoelectric detector I and the erbium-doped optical fiber amplifier II are added on the original basis, and an improved signal demodulation method is provided in combination, so that the problem that in the prior art, a straight waveguide phase modulator is adopte