镀膜长周期光纤光栅的单峰宽带滤波特性  

Broadband single-peak filtering characteristics of coated long-period fiber gratings

作　　者：陈海云[1,2] 顾铮■ 杨颖[3] 

机构地区：[1]上海理工大学光电信息与计算机工程学院,上海200093 [2]浙江师范大学信息光学研究所,金华321004 [3]上海理工大学理学院光电功能薄膜实验室,上海200093

出　　处：《物理学报》2012年第20期179-185,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:60777035);教育部科学技术研究重点项目(批准号:208040);上海市教育委员会科研项目(批准号:11ZZ131);上海市重点学科建设项目(批准号:S30502)资助的课题~~

摘　　要：镀膜长周期光纤光栅(LPFG)工作于相位匹配转折点时纤芯模与高次包层模的耦合产生单个宽带损耗峰,其3 dB带宽取决于纤芯模和包层模之间的色散差、光栅长度以及中心波长.研究表明,薄膜折射率和厚度的变化将影响纤芯模与包层模之间的色散差,从而影响损耗峰的3 dB带宽,同时损耗峰中心波长亦随之移动.薄膜折射率为1.57,厚度为350 nm时,损耗峰带宽可达302 nm.减小光栅长度在保证中心波长损耗大于6 dB的前提下可使损耗峰3 dB带宽增大至334 nm.进一步研究表明,在均匀LPFG中偏离光栅中点的适当位置引入单个π相移可以使带宽增大至372 nm以上.A coated long-period fiber grating （LPFG） operating at the phase-matching turning point couples the fundamental core mode to a higher-order cladding mode, producing a single broad-band whose 3dB-bandwidth is dependent on the difference in dispersion between the core mode and a cladding mode, grating length and central wavelength. The variations of film refractive index and thickness influence the difference in dispersion between the core mode and cladding mode and thus, the bandwidth of loss peak. The central wavelength of loss peak also varies with the changes of film parameters. When the film refractive index is 1.57 and the film thickness is 350 nm, the bandwidth of loss peak reaches 302 nm. The bandwidth can be further improved to 334 nm by reducing the grating length based on the fact that the loss at the central wavelength is guaranteed to be more than 6 dB. A further investigation shows that introducing a πphase shift into a uniform LPFG at a proper position that is away from the grating center can increase the bandwidth to 372 nm and more.

关 键 词：长周期光纤光栅 相位匹配转折点 3 dB带宽 相移长周期光纤光栅 

分 类 号：TN253[电子电信—物理电子学]