基于多模光纤光栅折射率传感的灵敏度研究

In this paper, in order to discuss the influence of high order modes in multimode optical fiber on liquid refractive index sensing, based on the current sensing theory, a structure combined multimode fiber with Bragg grating is used for liquid refractive index sensing, derived the relationship between the sensitivity and coremodes. In view of coremodes and core diameters,the paper compares and analyzes the sensing characteristics of two kinds of multi - mode fibers by simulation, higher order mode is more conducive to sensing and the sensitivity is increased when the core diameter decreased. Because of the strong evanescent wave effect at the core and liquid interface of multimode step fiber, it's superior to graded fiber sensing properties.