Quasi-Distributed Relative Humidity Sensing Based on Optical FMCW Multiplexed Fabry-Perot Interferometer

A quasi-distributed fiber optic relative humidity sensing system based on optical frequency modulated conti-nuous wave (FMCW) multiplexing Fabry-Perot interferometer (FPI) is proposed. In this paper, the fundamental structure and the locating principle are introduced, and the system layout and signal demodulation process are described in detail. Next, the sensing performance of the system is evaluated through humidity experiments. Finally, the stability of the system is tested by repeatability experiments. The system can be used for online monitoring of environmental humidity status and has significant application prospects for quasi-distributed sensing based on FPI.