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

Area of Science:

• Photonics and Optical Sensing
• Microwave Photonics
• Fiber Optic Sensors

Background:

• High-temperature environments pose challenges for accurate sensing.
• Multiplexing multiple fiber optic sensors is crucial for comprehensive monitoring.
• Existing optical Fourier-domain multiplexing requires specific cavity-length allocation.

Purpose of the Study:

• To propose and demonstrate a multiplexed high-temperature Fabry-Pérot (FP) fiber sensing system.
• To utilize dispersive microwave-photonic frequency-time domain analysis (DM-FTDA) for interrogation.
• To achieve multiplexing via delay-dominated discrimination for sensors with closely matched cavity lengths.

Main Methods:

• Incoherent broadband probing light modulated by RF signals.
• Reflection from a parallel network of hollow-core photonic crystal fiber FP (HCPCF-FP) sensors.
• Chirped fiber Bragg grating for dispersion and mapping spectral response to microwave transfer function.
• Delay-dominated discrimination using distinct delay fibers for each sensor branch.

Main Results:

• A three-sensor HCPCF-FP array was validated up to ~1000 °C.
• Linear time-shift responses were observed for individual sensors.
• Worst-case apparent inter-channel crosstalk was 2.46% under drift conditions.
• Successful demodulation of sensors with closely matched cavity lengths was achieved.

Conclusions:

• DM-FTDA is a scalable microwave-photonic interrogation framework.
• The system enables multiplexed FP sensing in harsh thermal environments.
• Complex optical acquisition is not required for this sensing approach.