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Microfabricated optical interference microphone for high signal-to-noise ratio up to 70.2 dB
Optics Express
|May 4, 2026
Summary
This study presents an optical MEMS microphone sensor, offering an ultra-low-noise alternative to capacitive sensors. The developed device achieves high sensitivity and low distortion for advanced acoustic detection.
Area of Science:
- Photonics
- Acoustics
- Microelectromechanical Systems (MEMS)
Background:
- Conventional capacitive sensing in MEMS microphones faces limitations for ultra-low-noise applications.
- Optical transduction offers a promising alternative for enhanced acoustic sensing.
Purpose of the Study:
- To demonstrate a prototype optical MEMS microphone sensor with optimized photonic-mechanical coupling.
- To evaluate its performance for high-fidelity acoustic detection.
Main Methods:
- Fabrication using standard micro-manufacturing processes with a low-bending-stiffness polysilicon diaphragm.
- Characterization of photonic-mechanical coupling and acoustic performance.
- Utilizing a balanced differential method for signal-to-noise ratio measurement.
Main Results:
- Achieved a frequency bandwidth of 200 Hz to 6.1 kHz.
- Obtained a sensitivity of 89.2 mV/Pa with low nonlinearity (max 2.97%) and repetitive error (1.11%).
- Demonstrated a signal-to-noise ratio of 70.2 dB, total harmonic distortion of 0.08%, and a wide dynamic range (0.1 to 1 Pa).
Conclusions:
- The optical MEMS microphone sensor shows significant potential as an ultra-low-noise acoustic sensor.
- Its performance characteristics are suitable for high-performance applications like medical auscultation and machine condition monitoring.
