Multiplexable tilted fiber Bragg grating sensors based on dispersive microwave-photonic frequency domain reflectometry

Tilted fiber Bragg gratings (TFBGs) have seen rapid development and widespread deployment in diverse sensing applications, ranging from biochemical detection to in-situ monitoring in energy systems. Their ability to generate rich spectral features via cladding mode coupling enables highly sensitive, multi-parameter, and label-free sensing. However, accurate interrogation typically requires broadband spectral measurements to resolve fine spectral structures—posing significant challenges for scalable and cost-effective multiplexing in practical settings. In this work, we propose and experimentally demonstrate a dispersive microwave-photonic frequency domain reflectometry (D-MPFDR) system for high-resolution, multiplexable TFBG interrogation. By integrating chromatic-dispersion-induced wavelength-to-time mapping with microwave frequency-domain reflectometry, the system reconstructs complete TFBG spectral information entirely in the RF domain. This enables each sensor to be both temporally resolved and spectrally analyzed. Experimental results verify the system’s high and tunable sensitivity through temperature and refractive index sensing. The multiplexing capability is further validated by simultaneously interrogating three TFBG devices with minimal crosstalk. This work presents a compact, scalable, and high-performance solution for real-time, multi-point fiber-optic sensing using TFBGs.