title: Method of hybrid multiplexing for fiber-optic Fabry-Perot sensors utilizing frequency-shifted interferometry.
abstract: Experimental and theoretical research on hybrid multiplexing for fiber-optic Fabry-Perot (F-P) sensors based on frequency-shifted interferometry is presented. Four F-P sensors multiplexed in a hybrid configuration were experimentally investigated. The location of each multiplexed sensor was retrieved by performing the fast Fourier transform, and the reflection spectrum of each sensor was also obtained in spite of the spectral overlap, which was consistent with the results measured by an optical spectrum analyzer. With theoretical modeling, the maximum sensor number of a two-channel hybrid multiplexing system reaches 26 with crosstalk of less than -50  dB and a maximum frequency-domain signal-to-noise ratio (SNR) of ∼25  dB, when the source power is 2 mW and the sensor separation is optimal, i.e., 40 m. And the sensor number is almost twice that multiplexed by a serial system under the same conditions. An SNR improvement of 3.9 dB can be achieved by using a Hamming window in a noise-free system compared with a Hanning window. In addition, we applied the experimental multiplexing system to a strain sensing test. The cavity lengths and cavity-length shifts of the four F-P sensors were demodulated, which was consistent with the actual situation. It provides a new feasible method to multiplex F-P sensors at large scale.
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Ou
authors.forename: Ciming
authors.initials: C
authors.lastname: Zhou
authors.forename: Angui
authors.initials: A
authors.lastname: Zheng
authors.forename: Chunfu
authors.initials: C
authors.lastname: Cheng
authors.forename: Dian
authors.initials: D
authors.lastname: Fan
authors.forename: Jiadi
authors.initials: J
authors.lastname: Yin
authors.forename: Hui
authors.initials: H
authors.lastname: Tian
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu