光学技术, 2020, 46 (1): 68, 网络出版: 2020-04-13
薄膜参数对镀膜长周期光纤光栅透射谱的影响
Influence of nano film overlay parameters on the transmission spectra of coated long period fiber gratings
镀膜长周期光纤光栅 有效折射率 谐振波长 最优膜厚 coated long period fiber gratings effective refractive index resonant wavelength optimum overlay thickness
摘要
基于四层光纤模型, 采用数值模拟方法, 研究了镀膜长周期光纤光栅的膜层折射率及厚度等参数对其传输谱特性的影响。结果表明, 随膜厚增加, 各包层模式有效折射率增大, 谐振波长向短波区漂移。当膜厚达到一定数值后, 有效折射率及谐振波长急剧变化, 长周期光纤光栅频谱出现模式转换现象, 模式跳变转折点对应最优薄膜厚度, 不同薄膜介质对应不同的最优膜厚, 研究对提高长周期光纤光栅传感器的敏感度具有重要的指导意义。
Abstract
Based on four-layer step-index waveguide modeling, the characteristics of long-period fiber grating (LPFGs) with an nm-thick film overlay are investigated and the influence of parameters such as overlay thickness, film refractive index are studied by numerical simulation. The results show that the effective refractive index of cladding modes increases and the resonance peaks shifts towards the shorter wavelength with the increase of film thickness. The shift of the effective refractive index and the resonance wavelength is drastic within a certain thickness range, which causes the mode transition of coated LPFGs. Turning point of mode transition corresponds to the optimum overlay thickness(OOT). The relation of the optimum thickness with overlay refractive index is also analyzed. All of the results can greatly improve the sensitivity of refractive index of the gratings.
高宇飞, 韩连福, 张勇, 刘超, 刘强, 付长凤. 薄膜参数对镀膜长周期光纤光栅透射谱的影响[J]. 光学技术, 2020, 46(1): 68. GAO Yufei, HAN Lianfu, ZHANG Yong, LIU Chao, LIU Qiang, FU Changfeng. Influence of nano film overlay parameters on the transmission spectra of coated long period fiber gratings[J]. Optical Technique, 2020, 46(1): 68.