Multiplexing of Fabry-Pérot Sensor by Frequency Modulated Continuous Wave Interferometry for Quais-Distributed Sensing Application

Fiber Fabry-Pérot (FP) sensor, as an optical sensor with simple structure and the most application fields, has attracted a lot of attention in recent decades, but it also faces the difficulty of multiplexing. In this paper, we propose and demonstrate a novel multiplexing method of FP sensor with multi-branch configuration interrogated with frequency modulated continuous wave interferometry. By an algorithm based on Fourier transform, the sub-sensors are addressable and their interference spectrum can be demodulated independently. For demonstration, the quasi-distributed refractive index (RI) sensing experiment is realized. The experiment results inherit high RI sensitivity of the traditional FP sensor around 1200 nm/RIU and high RI resolution smaller than 5 × 10 ^-6 RIU. Besides, thanks to the advantage of coherence detection, the spectrum can be demodulated from the reflection signal of <; 2 pW, which provides the possibility for a huge multiplexing amount, about 8000 in theory. The proposed multiplexing method is significant for practical applications of the traditional FP sensor.