The idea of applying a simple Fabry–Perot fiber laser (FPFL) set-up in a free-running condition as an acoustic sensing medium is proposed. Conventional optical microphone requires a stringently aligned diaphragm to mediate the acoustic impedance mismatch between air and silica fiber. Motivated by the difficulty of optical sensing of airborne acoustic waves, a new sensing method is proposed to sense acoustic waves without the assistance of a diaphragm as transducer. By studying the output power fluctuation of the FPFL, the operating bandwidth and sensitivity of the proposed sensing method are determined. The tunability of the resonant frequency from 5 kHz to 85 kHz allows sensing of acoustic waves in the range of 100 Hz to 100 kHz. Tuning of the resonant frequency can be performed by changing the optical pumping power from as low as 10 mW to 68.5 mW or higher.
© 2012 Optical Society of America
Original Manuscript: September 28, 2011
Revised Manuscript: January 19, 2012
Manuscript Accepted: February 9, 2012
Published: May 11, 2012
Chang Hong Pua, Harith Ahmad, Sulaiman Wadi Harun, and Richard M. De La Rue, "Direct airborne acoustic wave modulation of Fabry–Perot fiber laser (FPFL) over 100 kHz of operating bandwidth," Appl. Opt. 51, 2772-2777 (2012)