Sensitivity improvement of fiber optic interferometric hydrophone based on composite structure

Area of Science:

• Optoelectronics
• Acoustics
• Materials Science

Background:

• Fiber optic hydrophones are crucial for underwater acoustic detection.
• Existing designs face limitations in sensitivity and frequency response.
• Improving hydrophone performance is key for enhanced underwater surveillance and research.

Purpose of the Study:

• To develop a high-performance fiber optic interferometric hydrophone using a novel composite structure.
• To enhance detection sensitivity and broaden the frequency response range.
• To enable more effective underwater weak signal detection.

Main Methods:

• Theoretical analysis and numerical simulation to investigate axial stress effects on the composite structure.
• Design and fabrication of a fiber optic hydrophone incorporating a thick hollow column.
• Experimental validation of the hydrophone's sensitivity and minimum detectable pressure.

Main Results:

• The composite structure fiber optic hydrophone achieved an average sensitivity of -113.25 dB re rad/µPa from 10 Hz to 3 kHz.
• Sensitivity was approximately double that of the standard push-pull fiber optic hydrophone structure.
• Minimum detectable pressure (MDP) was 2 µPa/√Hz at 1 kHz and 0.56 mPa/√Hz at 10 Hz, an improvement of at least 6 dB over state-of-the-art designs.

Conclusions:

• The proposed composite structure significantly enhances fiber optic hydrophone sensitivity and detection performance.
• The hydrophone demonstrates excellent potential for underwater weak signal detection applications.
• The design offers a substantial improvement over existing fiber optic hydrophone technologies.