Microwave Photonics-Assisted Interrogation of Fiber-Optic Interferometric Sensors With Joint Frequency-Time Domain Analysis

Fiber-optic interferometers are widely used in localized sensing applications due to their compact size, high sensitivity, and immunity to electromagnetic interference. In this paper, we propose and experimentally demonstrate a novel interrogation scheme for fiber-optic interferometric sensors, utilizing microwave photonics (MWP) and joint frequency-time domain analysis. As a proof of concept, a miniature fiber in-line Fabry-Perot interferometer (FPI) is integrated with a microwave photonic single-passband filter, enhanced by a dispersion compensation module to improve sensing performance. By applying an inverse Fourier transform to the system's complex frequency response, the time-domain representation of the signal is obtained, translating spectral shifts of the FPI into precise variations in time delay. The system offers tunable sensitivity through adjustable dispersion coefficients and achieves high-sensitivity strain measurements. Additionally, multiplexed sensing with minimal crosstalk is demonstrated through the joint frequency-time domain analysis, using phase information from the time-domain signal. The results confirm the effectiveness of the proposed MWP-based interrogation technique, demonstrating enhanced sensitivity, robustness, and applicability in multi-point sensing for advanced optical fiber sensing systems.