Orthogonal phase demodulation system with wide frequency band response based on birefringent crystals and polarization technology

The orthogonal phase demodulation method can effectively avoid the problem of the working interval of the optical fiber Fabry-Perot (F-P) sensor and has high accuracy. Based on the principle of the low-coherence interference, polarizers and birefringent crystals are used to construct signals with orthogonal relationships in the orthogonal phase demodulation system. Four-quadrant inverse tangent operation is used to accurately calculate the phase value. In order to verify the frequency band response of the demodulation system, the acoustic signals of frequencies in the range of 200 Hz-25 kHz are interrogated. Experimental results show that the orthogonal phase demodulation system can be appled to demodulate the signals of wide frequency band. The research has value for the promotion and application of orthogonal phase demodulation system based on birefringent crystals and polarization technology