保偏微结构光纤光栅F-P腔折射率传感特性分析

摘要

To enhance the stability of the fiber grating refractive index sensor and increase the grating reflectivity, the Polarization Maintaining Microstructured Optical Fiber (PM-MOF) grating Fabry-Perot (F-P) cavity is proposed. Based on Finite Element Method (FEM) and Transfer Matrix Method (TMM), the refractive index sensing characteristics of the sensor is analyzed. The relationship between the refractive index and resonant wavelength difference is simulated. Moreover, the dependence of the reflection spectrum on the center big holes size and the F-P cavity length is studied. Since two polarization modes respond similarly to the outside perturbation, the fiber possesses high stability. Based on the interference, the reflectivity is enhanced obviously, and almost remains unchanged as the analyte refractive index increasing. It is beneficial for the detection. The results provide the theoretical basis for the application of PM-MOF grating in the optical fiber refractive index sensor and the optical fiber label-free biosensing.%针对提高光纤光栅折射率传感器抗干扰能力以及增加反射率的需求,本文提出了一种基于Fabry-Perot腔的保偏微结构光纤(PM-MOF)布拉格光栅折射率传感器.根据传榆矩阵法和有限元方法,分析了微结构光纤光栅F-P腔中被测物折射率与F-P腔反射谱中两个偏振模谐振波长差的关系,在此基础上讨论了中心孔直径、F-P腔长度等参数对传输特性的影响.研究结果表明,随着空气孔中填充物折射率的增加,保偏微结构光纤光栅F-P腔的两个偏振态的谐振波长差将逐渐减小；F-P腔的干涉作用使反射率较单个光栅有很大提高,便于长距离传输和实时解调；两个偏振模对外界干扰具有相似的响应,因此该传感器具有更强的抗干扰能力.本文研究结果为保偏微结构光纤光栅在折射率传感器及其生物传感器方面的应用提供了理论依据.