Integrated design of an anti-polarization-fading UWFBG distributed acoustic sensing system

This Letter proposes an integrated distributed acoustic sensing (DAS) system based on an ultra-weak fiber Bragg grating (UWFBG) array with anti-polarization-fading capability. Conventional anti-polarization-fading DAS architectures suffer from high system complexity and lack real-time demodulation, limiting their deployment in engineering applications. To suppress polarization fading and overcome these limitations, the proposed system integrates orthogonally polarized dual-pulse generation using a polarization switch (PSW) with an improved differential-cross-multiplication (DCM) algorithm to demodulate three interferometric signals. A fully integrated dual-pulse demodulation scheme is implemented on a field-programmable gate array (FPGA), substantially reducing system complexity while enabling real-time processing. Experimental results show that the system effectively suppresses polarization fading, reduces background phase noise, and enhances the minimum detectable acoustic pressure, maintaining stable performance with an average signal-to-noise ratio (SNR) of 33.83 dB and a standard deviation of 2.81 dB.