Multiplexed Fabry-Pérot high-temperature sensing based on dispersive microwave-photonic frequency-time domain...

We propose and experimentally demonstrate a multiplexed high-temperature Fabry-Pérot (FP) fiber sensing system interrogated by dispersive microwave-photonic frequency-time domain analysis (DM-FTDA). In the proposed architecture, incoherent broadband probing light is modulated by radio-frequency (RF) signals and then reflected by a parallel network of hollow-core photonic crystal fiber FP (HCPCF-FP) sensors. A chirped fiber Bragg grating provides strong dispersion to map the composite FP spectral response into a well-defined microwave transfer function. Unlike conventional optical Fourier-domain multiplexing that requires deliberate cavity-length allocation, the proposed approach achieves multiplexing via delay-dominated discrimination. Distinct delay fibers are assigned to each sensor branch, and an inverse Fourier transform of the measured RF response produces separable time-domain features for individual sensors, enabling demodulation for sensors with closely matched cavity lengths. A three-sensor HCPCF-FP array is validated to ∼1000 °C, exhibiting linear time-shift responses, with worst-case apparent inter-channel crosstalk of 2.46% under the present drift conditions. These results establish DM-FTDA as a scalable microwave-photonic interrogation framework for multiplexed FP sensing in harsh thermal environments without complex optical acquisition.