Extrinsic fiber acoustic sensors have attracted considerable interest due to their exceptional sensitivity and extremely low minimum detectable pressure (MDP). However, this high sensitivity also introduces excessive phase drift, resulting in significant 1/f noise and complicating the demodulation process. In this study, we present a stabilized triple-phase demodulation (STPD) method that effectively suppresses 1/f noise and maintains a stable, drift-free phase output, achieving a low and flat noise floor of 173 μrad/Hz without the need for prior calibration. To further enhance performance, we design a labyrinth-inspired multiresonant membrane that enables broadband acoustic detection. As a result, the proposed sensor achieves a wideband response from 20 Hz to 15 kHz, a maximum phase sensitivity of 1.02 rad/Pa (−119.83 dB ref: 1 rad/μPa), and an MDP as low as 81.84 μPa/Hz at its first-order resonance. The system also demonstrates an impressive linear dynamic range of 115.72 dB, enabling reliable sound detection across a broad range of pressures.Extrinsic fiber acoustic sensors have attracted considerable interest due to their exceptional sensitivity and extremely low minimum detectable pressure (MDP). However, this high sensitivity also introduces excessive phase drift, resulting in significant 1/f noise and complicating the demodulation process. In this study, we present a stabilized triple-phase demodulation (STPD) method that effectively suppresses 1/f noise and maintains a stable, drift-free phase output, achieving a low and flat noise floor of 173 μrad/Hz without the need for prior calibration. To further enhance performance, we design a labyrinth-inspired multiresonant membrane that enables broadband acoustic detection. As a result, the proposed sensor achieves a wideband response from 20 Hz to 15 kHz, a maximum phase sensitivity of 1.02 rad/Pa (−119.83 dB ref: 1 rad/μPa), and an MDP as low as 81.84 μPa/Hz at its first-order resonance. The system also demonstrates an impressive linear dynamic range of 115.72 dB, enabling reliable sound detection across a broad range of pressures.
