Refractive Index Sensing Characteristics of Fiber Bragg Grating in the Polarization Maintaining Microstructured optical Fiber

Refractive index sensing characteristics of a polarization maintaining microstructured optical fiber (PM-MOF) Bragg Grating is investigated in this paper. Based on Finite Element Method (FEM) and the coupled-mode theory, the reflection spectrum of the PM-MOF Bragg grating is analyzed. The analysis results show that when the air holes are injected with analyte, the resonant wavelengths of the two polarization modes will drift. Furthermore the relationship between the difference of two polarization modes resonant wavelengths and the analyte refractive index is considered. The novelty of this work lies in the high stability of the fiber from that of two polarization modes responding similarly to the outside perturbation. Furthermore, the two center big air holes have great impact on the detection sensitivity. In order to select the most appropriate fiber, the impact of the central big air holes is discussed. The investigations in this paper provide the theoretical basis for the optical fiber biosensor.