A Novel Two-Dimensional Hydrophone Based on Fiber Bragg Gratings

Area of Science:

• Photonics and Sensing Technologies
• Underwater Acoustics
• Biomedical Engineering

Background:

• Underwater acoustic detection is crucial for various applications.
• Existing hydrophones face limitations in sensitivity and localization accuracy.
• Fiber-optic sensors offer potential for enhanced performance.

Purpose of the Study:

• To develop a high-sensitivity two-dimensional fiber-optic hydrophone.
• To improve the detection and localization of underwater acoustic sources.
• To leverage fiber Bragg gratings (FBGs) and novel structural designs for enhanced acoustic sensing.

Main Methods:

• Fabrication of a two-dimensional hydrophone with two orthogonally placed sensing heads.
• Integration of fiber Bragg gratings (FBGs) within a 3D-printed encapsulation.
• Utilization of a silicone thin-film and pyramidal channel to concentrate acoustic energy and enhance FBG strain.
• Optical demodulation of acoustic frequency response using a photodetector.

Main Results:

• Achieved a peak sensitivity of -210.59 dB re 1 V/μPa.
• Demonstrated a figure of merit (FOM) up to 3.64 dB/Hz.
• Obtained a limit of detection (LOD) of 64.19 dB re 1 μPa (10-400 Hz).
• Confirmed high sensitivity and accurate source localization capabilities through experimental validation.

Conclusions:

• The developed two-dimensional fiber-optic hydrophone exhibits high sensitivity and localization accuracy.
• The innovative design, incorporating FBGs and a pyramidal channel, significantly enhances underwater acoustic sensing.
• This technology holds substantial potential for advanced underwater acoustic detection and monitoring applications.