提高制作光纤光栅时飞秒激光光斑质量的方法  

Improvement of spot quality in femtosecond laser point-by-point inscription of fiber gratings

作　　者：朱学华[1] 潘玉寨[1] 王莎莎[1] 苏晓慧[1] 

机构地区：[1]哈尔滨工业大学(威海)光电科学系,山东威海264209

出　　处：《红外与激光工程》2012年第7期1750-1754,共5页Infrared and Laser Engineering

基　　金：山东省自然科学基金(ZR2010FQ017);哈工大科研创新基金(HIT.NSRIF.2009146);威海市科技计划项目(2011DXGJ09)

摘　　要：由于光纤自身固有的圆柱形结构,在飞秒激光逐点刻写光纤布拉格光栅过程中会产生柱透镜效应,使得聚焦光斑呈长条状,对刻写光栅结构产生不利影响。基于几何光学原理分析了产生长条状光斑的原因,并提出了一种有效地改善聚焦光斑质量的方法。实验中,将待写光纤夹在玻璃板之间并填充折射率匹配液,运用800 nm钛蓝宝石飞秒激光通过50×显微物镜聚焦在双包层光纤内,单脉冲曝光后得到了直径为1.5μm圆形光斑,方法简单,易于操作。光斑质量的提高扩展了飞秒激光在光纤微细结构制作中的应用。The influence of the intrinsic fiber geometry on the laser beam focusing during the point-by- point inscription of fiber Bragg grating （FBG） was highlighted. The laser induced spot shows a strip profile because of the fiber cylindrical lens effect. The reason for this cylindrical lens effect was analyzed based on the principle of geometrical optics, and an effective method was used to improve spot quality. During the experiment, a fiber was immersed into the refractive index match oil whose index is 1.47, then a period structure with single pulse induced was inscribed into the core of this LMA double- cladding fiber by 50x microscope objective focused femtosecond laser. At last, the cylindrical lens effect was eliminated and the circle spot with the diameter of 1.5 μm was realized. There should be a very wide range of application in fiber microstructure fabricating.

关 键 词：飞秒激光直写 聚焦光斑 光纤布拉格光栅 折射率匹配液 

分 类 号：TN253[电子电信—物理电子学]