镀含弱吸收膜两层膜系长周期光纤光栅谐振特性及其优化  

Resonant Characteristics and Optimization of Long Period Fiber Grating Coated with Weak Absorption Double-layer Films

作　　者：邓传鲁[1] 顾铮■ 张江涛[1] 

机构地区：[1]上海理工大学理学院光电功能薄膜实验室,上海200093

出　　处：《光子学报》2009年第11期2873-2879,共7页Acta Photonica Sinica

基　　金：国家自然科学基金(60777035);教育部科学技术研究重点项目(208040);上海市教育委员会科研项目(07ZZ87);上海市重点学科建设项目(T0501)资助

摘　　要：采用严格的耦合模理论,建立了两层膜系长周期光纤光栅复特征方程,用微扰法对复特征方程进行求解,结果和D.V.Ignacio的结论相符.求得的谐振波长表明其随膜层厚度和膜层折射率变化明显,受消光系数影响很小.重点提出了两种途径来优化膜层参量组合,以获得较大的谐振波长偏移量,计算结果显示,参量组合取值为(h3=122.76nm,h4=400nm)和(n3=1.5722,h4=400nm)时,谐振波长偏移量分别为10.35nm和11.74nm,远高于只镀一层敏感膜LPFG的偏移量2.78nm,从而证明敏感膜层厚度(h4)较大的参量组合可提高传感器的灵敏度.Based on the coupled-mode theory,the complex characteristic equation of LPFG coated with weak absorption double-layer films is set up.By use of the perturbation method,the complex root is obtained.The result is coincident with the result of D.V.Ignacio.The film thickness and refractive index have a great influence on the resonant wavelength,but the extinction coefficient has a little influence on the resonant wavelength.And,the two methods of optimizing the film parameters are presented in order to obtain the larger shifts of the resonant wavelength.The results show that when the film parameter combinations are h3=122.76 nm,h4=400 nm and n3=1.572 2,h4=400 nm,the wavelength shifts are 10.35 nm and 11.74 nm,respectively,which is much larger than the value of 2.78 nm obtained from the LPFG coated single film.It proves that the selection of the thicker film increase the sensitivity.

关 键 词：长周期光纤光栅 弱吸收薄膜 敏感膜 透射谱 

分 类 号：TP212.14[自动化与计算机技术—检测技术与自动化装置]