Dual-Wavelength Differential Cross Multiplication Method for Fast Temperature Interrogation with Fiber-optic Fabry-Pérot Interferometers

This paper proposes a novel fast-response seawater temperature demodulation method employing the dual-wavelength differential cross multiplication (DWDCM) algorithm. The Fabry-Pérot interferometer-based temperature sensor probe is fabricated from a double-side-polished thin silicon plate, demonstrating the effectiveness of DWDCM demodulation for high-frequency temperature measurements. Experimental results show that our FPI temperature sensor achieves ultra-fast temperature sampling with high accuracy and rapid response time constant of $\pm 0.0046{ }^{\circ} \mathrm{C}$ and 6.0 ms, respectively. These features provide competitive advantages in ocean turbulent temperature measurements, especially for mobile marine platforms with internal autonomous logging mode required.