Detection of Low Frequency Signals using Interferometric Fiber Sensors based on Phase Generated Carrier Demodulation Technique

Abstract

A fiber-optic sensor is a sensor with high sensitivity, and signal detection technology is one of its key technologies. Phase generated carrier demodulation technology is a homodyne demodulation method widely used for interference fiber-optic sensors. Research reveals that the amplitude of the interference signal and the modulation depth will affect the result of demodulation. The distortion of the demodulated signal can be reduced by the elimination of the effects of the interference signal amplitude and modulation depth. A phase generated carrier demodulation method for interference fiberoptic sensors is proposed to detect weak ELF signals. Theoretical analysis and simulation have been implemented on the demodulation of weak ELF signals using low-level submixer carrier. The results indicate that in the demodulation of weak ELF signals, DC drift occurs in the DCM approach, while the Arctangent approach does not have this problem. Then, an optical fiber sensing system for ELF signals is established based on optical fiber interferometer, indicating the Arctangent approach is able to demodulate the VLF signals accurately.