Integrated stealth-sensing fiber-optic sensor via Dirac-cone phononic crystal.

Area of Science:

• Acoustic Engineering
• Materials Science
• Photonics

Background:

• Integrating underwater acoustic stealth with fiber-optic sensing is challenging due to material interference with sound waves.
• Conventional stealth methods often degrade the acoustic signals needed for detection.

Purpose of the Study:

• To develop a hybrid acoustic sensing node that achieves both platform stealth and enhanced acoustic signal acquisition.
• To demonstrate a novel approach for integrating fiber-optic hydrophones with acoustic stealth structures.

Main Methods:

• Monolithic integration of a fiber laser hydrophone with a 2D pillar-array phononic crystal.
• Engineering the phononic crystal using Dirac-cone dispersion and quadrupole-mode coupling for acoustic manipulation.
• Utilizing the phononic crystal to create a perfect acoustic stealth region and redirect acoustic energy.

Main Results:

• The phononic crystal created a 60mm x 60mm acoustic stealth region at 48.16 kHz.
• Acoustic backscattering was significantly reduced, and sound pressure detection was enhanced by ~6.18 dB.
• Anisotropic wave response enabled directional acoustic sensing from a single element.

Conclusions:

• The proposed hybrid node offers a practical strategy for simultaneous concealment and enhanced underwater acoustic sensing.
• This technology provides a compact solution for directional sensing with improved sensitivity.