A simultaneous audio and temperature sensing system based on in-line Mach-Zehnder interferometer

A system integrating audio and temperature sensing capabilities has been developed for simultaneous detection. Within this system, an in-line Mach-Zehnder interferometer (IMZI) sensor has been explored. Manufactured using the electro-discharge method, the sensor comprises a structure connecting single mode fiber (SMF) to polarization-maintaining fiber (PMF) and then back to SMF, with distinctive peanut-shaped junctions. The sensor's sensitivity to temperature and curvature has been assessed to determine its potential for simultaneous audio and temperature detection. Within the temperature range of 15 degrees C-48 degrees C and a curvature range of 0 m-1-0.06654 m-1, the peak sensitivities observed were-0.1072 nm/degrees C and 63.5569 nm/m-1, respectively. Experimental verification confirmed the system's audio performance using the proposed IMZI sensor. The system operates over a broad frequency range from 20 Hz to 20,000 Hz. The maximum frequency response and minimum detectable pressures (MDP) are 1804.92 mV/Pa and 11.74 mu Pa/Hz1/2 at 800 Hz, respectively, indicating notable acoustic sensitivity. Based on both theoretical analyses and empirical methodologies, the system successfully achieves simultaneous audio and temperature detections. This is accomplished by process-ing the detected data of curvature and temperature variations via high-speed sampling and dual-wavelength demodulation. Notably, this approach addresses and overcomes the sensitivity reduction experienced by acoustic sensors based on interferometers due to temperature-induced Q point drifts.