All-optical low noise fiber Bragg grating microphone.

Area of Science:

• Photonics
• Acoustics
• Fiber Optics

Background:

• Traditional microphones often face limitations in sensitivity and miniaturization.
• Fiber optic sensing offers a promising avenue for developing novel acoustic transducers.

Purpose of the Study:

• To design and demonstrate an all-fiber microphone.
• To achieve high sensitivity in acoustic pressure detection using fiber optic components.

Main Methods:

• An all-fiber design incorporating a fiber Bragg grating Fabry-Perot resonator attached to a diaphragm transducer.
• Analytical modeling and verification of the fiber-diaphragm mechanical interaction.
• Utilizing the Hänsch-Couillaud readout technique for enhanced sensitivity.

Main Results:

• Achieved a noise-equivalent strain sensitivity of 7.1×10^-12 ε/Hz.
• Demonstrated a sound pressure sensitivity of 74 μPa/√Hz at 1 kHz.
• Obtained a signal-to-noise ratio of 47±2 dB with a 1 Pa drive at 1 kHz.

Conclusions:

• The developed all-fiber microphone design shows significant potential for sensitive acoustic measurements.
• The results align well with theoretical modeling, validating the proposed approach.
• This technology could lead to advancements in fiber optic sensing for acoustic applications.