薄膜长周期光纤光栅双峰谐振效应特性研究

Properties of Dual Peak Resonant of Coated Long Period Fiber Grating

归于长周期光纤光栅的严格的相位匹配条件,研究了光栅周期、平均折射率变化、环境折射率和薄膜参数对长周期光纤光栅双峰效应的影响。研究发现光栅周期和平均折变量增加可以减小双峰距离,但平均折变量的增加极易导致光谱特性变差。给出了双峰距离随环境折射率变化的关系,发现应用镀膜长周期光纤光栅的双峰谐振效应可以有效提高光栅的折射率灵敏度。研究还发现,通过减小薄膜厚度或薄膜折射率可以减小两谐振峰之间的距离。

Based on the strict phase-matching formula conditions, the grating period, the average refractive index change, environmental refractive index and the effect of film parameters on the dual peak resonant of coated long-period fiber grating are studied in details. The study shows that the distance will be reduced when the grating period or the average refractive index charge increases, and the increase of the average refractive index can easily lead to deterioration of the spectral characteristics. It is given that the distance between two resonant peaks of Coated LPFG changes with the environmental refractive index, and the application of the dual peaks resonant effect of coated long-period fiber grating can greatly improve the sensitivity of the refractive index of the gratings. The study also finds that the distance between the two resonance peaks can be reduced by reducing the film thickness or refractive index.