多层光纤布拉格光栅的理论与实验研究

Theoretical and Experimental Investigation of Fiber Bragg Gratings Written in Multilayer Single Mode Fibers

从理论和实验两方面研究了在非周期性多层光纤上写入布拉格光栅的光学特性。从耦合模理论出发,讨论了光纤具有多于一个光敏层的情况。在实验室自制的两类多层光纤上写入光栅的实验也表明,该类光栅具备有一般光栅的普遍光学特性,说明在使用多层光纤作为关键部分构建器件时,需要的各类光栅部件能够通过直接在该类光纤上写入光栅实现。紫外光在氢载掺铒多层光纤上写入光栅的实验说明分层的异种元素掺杂将导致芯区应力增加,从而辅助提高光纤的光敏性。

The optical properties of gratings written in nonperiodical multilayer fibers are investigated both theoretically and experimentally. The coupled-mode theory for gratings is extended to be applicable to the fibers with more than one photosensitive layers. The experimental results of fiber Bragg gratings written in laboratory-fabricated ordinary and Er3＋ doped multilayer single mode fibers confirm that such gratings possess the common characteristics of the gratings written in ordinary one-layer-core fibers, which indicates that in a device using multilayer fiber as its critical part, gratings written in the multilayer fibers are able to fulfill the requests for grating parts. The experimental results also suggest that the inter-layer stress in core area may be a major cause of photosensitive compensation for hydrogen-loaded Er^3＋ doped multilayer fiber.