Stability-enhanced low-frequency fiber optic hydrophone based on an extrinsic Fabry-Perot interferometer

Area of Science:

• Photonics
• Acoustics
• Materials Science

Background:

• Fiber optic hydrophones (FOHs) provide electromagnetic interference resistance but face challenges in stable, high-performance, low-cost underwater operation.
• Existing hydrophone technologies often struggle with complex underwater environments and cost-effectiveness.

Purpose of the Study:

• To develop a miniaturized, cost-effective fiber optic hydrophone.
• To overcome limitations of traditional hydrophones in challenging underwater settings.
• To achieve stable, high-performance acoustic sensing.

Main Methods:

• Fabrication of a miniaturized fiber optic hydrophone using an extrinsic Fabry-Perot interferometer (EFPI).
• The EFPI sensor incorporates a composite chromium-aluminum (Cr-Al) membrane and fiber.
• Linear demodulation technique employed to suppress output spectrum drift.

Main Results:

• The developed sensor exhibits an average sound pressure sensitivity of -139.15 dB re 1 V/µPa.
• The equivalent noise sound pressure at 1 kHz is measured at 51.52 dB re 1 µPa/Hz^1/2.
• The sensor demonstrates sensitive low-frequency response and favorable noise performance.

Conclusions:

• The miniaturized EFPI-based FOH offers a promising solution for low-cost, stable, and high-performance underwater acoustic sensing.
• The sensor's design and performance characteristics make it suitable for various underwater applications requiring sensitive detection.
• Further potential exists for this sensor due to its sensitive low-frequency response and noise performance.