Acoustic sensing based on a dual-chirped-comb interferometric ranging system

Fiber-optic acoustic sensors based on diaphragms provide a potential alternative for wideband acoustic detection due to their simple structure, excellent phase consistency, and strong immunity to electro-magnetic interference. Conventional demodulation techniques—intensity and phase demodulation. However, these methods can only detect relative displacements caused by acoustic vibrations, lacking the capability for real-time measurement of absolute distance. To address these challenges, we propose an acoustic sensing method based on a dual-chirped-comb interferometric ranging system, which enables both absolute distance measurement of the sensing points and demodulation of acoustic signals. The system achieves a 100-kHz measurement rate and a 1.5-km non-ambiguity range, while maintaining a precision of about 10 μm, making it applicable for real-time acoustic monitoring.