An Acoustic Sensor Based on Active Fiber Fabry-Pérot Microcavities

Area of Science:

• Photonics
• Acoustic Sensing
• Optical Engineering

Background:

• Development of active acoustic sensors is crucial for various applications.
• Existing sensors often face limitations in sensitivity, cost, or network integration.
• Fiber optic sensing offers potential for robust and compact sensor designs.

Discussion:

• A high-finesse fiber Fabry-Pérot micro-cavity with a gain medium was engineered as an active acoustic sensor.
• The sensor operates by modulating laser frequency with acoustic pressure, converted to beat signals via an interferometer.
• The device lases at 1535 nm, is optically pumped, and exhibits tunable output over a 10 nm range.

Key Insights:

• Achieved high sensitivity of 2.6 V/Pa and a noise equivalent acoustic signal level of 230 μPa/Hz1/2 at 4 kHz.
• Demonstrated a wide frequency response from 100 Hz to 18 kHz.
• The sensor is low-cost, easily fabricated, and requires no external lasers or demodulators.

Outlook:

• The sensor's communication wavelength operation and electrical tunability facilitate dense wavelength division multiplexing (DWDM) for multi-sensor networks.
• Potential applications include remote oil and gas leakage exploration, photo-acoustic spectrum detection, and sound source localization.
• This technology offers a promising, cost-effective solution for advanced acoustic monitoring.