Curved Fabry-Pérot Ultrasound Detectors: Optical and Mechanical Analysis.

Area of Science:

• Optical Physics
• Biomedical Engineering
• Materials Science

Background:

• Optical fiber acoustic detectors for medical ultrasound imaging typically use planar Fabry-Perot cavities.
• Current fabrication methods like dip-coating limit sensor geometry and performance.
• Lab-on-Fiber technology allows for complex 3D structures with controlled geometric parameters.

Purpose of the Study:

• To numerically analyze the impact of curvature on optical and acoustic properties of plano-concave Fabry-Perot cavities.
• To compare the performance of curved cavities with planar configurations for ultrasound detection.
• To establish design rules for high-performance optical fiber acoustic probes.

Main Methods:

• Finite Element Method (FEM) for numerical analysis.
• Simulation of optical and mechanical properties of curved plano-concave cavities.
• Comparison of sensitivity, bandwidth, and directivity metrics against planar designs.

Main Results:

• Curvature significantly enhances sensitivity (up to 2.5x at L=60 μm) by improving light confinement.
• Curved structures maintain high spectral quality (FOM) even with fabrication perturbations.
• Mechanical analysis shows no compromise in acoustic response or bandwidth (~40 MHz).

Conclusions:

• Curved plano-concave structures are robust for high-sensitivity polymeric Lab-on-Fiber ultrasound detectors.
• This design offers improved performance and fabrication tolerance for MHz-scale bandwidth applications.
• Optimized sensor geometry is key to advancing optical fiber-based ultrasound imaging.