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

Area of Science:

• Photonics and Sensing Technologies
• Fiber Optic Sensing
• Signal Processing

Background:

• Conventional distributed acoustic sensing (DAS) systems face challenges with polarization fading, high complexity, and lack of real-time demodulation.
• These limitations hinder the practical deployment of DAS in demanding engineering applications.

Purpose of the Study:

• To propose and demonstrate an integrated DAS system with enhanced anti-polarization-fading capability.
• To overcome the limitations of existing DAS architectures by enabling real-time processing and reducing system complexity.

Main Methods:

• Integration of an ultra-weak fiber Bragg grating (UWFBG) array with anti-polarization-fading capability.
• Utilizing orthogonally polarized dual-pulse generation via a polarization switch (PSW).
• Employing an improved differential-cross-multiplication (DCM) algorithm for demodulating three interferometric signals, implemented on a field-programmable gate array (FPGA) for real-time processing.

Main Results:

• Effective suppression of polarization fading.
• Significant reduction in background phase noise.
• Enhanced minimum detectable acoustic pressure.
• Stable system performance with an average signal-to-noise ratio (SNR) of 33.83 dB and a standard deviation of 2.81 dB.

Conclusions:

• The proposed integrated DAS system successfully addresses polarization fading and real-time processing limitations.
• The system demonstrates improved performance metrics, including SNR and sensitivity.
• This advancement facilitates more robust and practical deployment of DAS in various engineering fields.