Equivalent Self-Noise Suppression of Distributed Hydroacoustic Sensing System Using SDM Signals Based on Multi-Core...

Area of Science:

• Optics
• Acoustics
• Fiber Optics Sensing

Background:

• Distributed hydroacoustic sensing systems require effective self-noise suppression.
• Enhancing acoustic sensitivity and signal-to-noise ratio (SNR) is crucial for detecting weak underwater signals.

Purpose of the Study:

• To propose and validate a method for enhancing acoustic sensitivity and SNR in distributed hydroacoustic sensing.
• To reduce equivalent self-noise using space division multiplexing (SDM) technology with multi-core fiber (MCF).

Main Methods:

• A dual-channel demodulation system for distributed acoustic sensing was designed using MCF.
• The acoustic pressure phase sensitivity (APPS) and SNR gain were analyzed through dual-channel signal accumulation.
• Experimental verification was performed to validate the proposed method.

Main Results:

• The self-noise correlation coefficient between MCF cores was found to be 0.11, increasing noise power by 3.46 dB.
• Accumulating dual-core signals increased APPS by 5.97 dB re 1 rad/μPa, nearing the theoretical 6 dB.
• Equivalent self-noise was reduced by 2.54 dB.

Conclusions:

• Space division multiplexing (SDM) of multi-core signals effectively enhances acoustic pressure phase shift sensitivity and SNR.
• The proposed MCF-based SDM method significantly suppresses equivalent self-noise in hydroacoustic sensing systems.
• This technique is vital for the accurate detection of weak underwater acoustic signals.