Monitoring Multiple Hi-Bi Sensing Fibers in a Single Fiber Loop Mirror

In this paper, multiple high-birefringence (Hi-Bi) sensing fibers have been multiplexed and validated as strain and temperature sensors in a single fiber loop mirror interferometer. The strain and temperature applied to each fiber section have been measured in the spatial frequency domain without crosstalk by means of the fast Fourier transform. The Hi-Bi sensing fibers are fused together with a rotation angle given by the theoretical analysis of the structure, reducing the number of polarization controllers needed in the system and greatly simplifying the operation of the system. Additionally, full-polarization maintaining version of the setup, which does not need any polarization controller, is also presented and validated both theoretically and experimentally.