Tunable-laser-enabled hybrid wavelength-scanning interferometry toward temperature-compensated acoustic pressure sensing

Fiber-optic acoustic sensors are vital in structural health monitoring, photoacoustic spectroscopy, and biomedical applications. Achieving simultaneous measurement of quasi-static temperature and dynamic acoustic vibration with effective decoupling remains challenging. In this work, we propose an integrated fiber-optic sensor probe with dual Fabry-Perot (FP) cavities: a silicon-based cavity for temperature sensing and a diaphragm-based air cavity for acoustic pressure sensing. A novel hybrid interferometry is introduced, employing programmable modulation of a tunable Modulated grating Y-branch (MG-Y) laser to combine coarse wavelength scanning (20 kHz) at 1530 nm for acoustic measurement and dense wavelength scanning (10 Hz) at 1550 nm for temperature measurement, using a single demodulation system. Experimental results demonstrate a linear temperature response (<i>R</i>²=0.996) from 27°C to 56°C. Crucially, by leveraging real-time temperature compensation, the maximum acoustic pressure measurement error was reduced from 28.4% to 4.6%, validating the system's efficacy in high-precision, temperature-compensated acoustic metrology.