Mi Yuean, Li Haisu, Ren Guobin
Appl Opt. 2017 Sep 1;56(25):7305-7310. doi: 10.1364/AO.56.007305.
We propose a vector mode conversion approach based on asymmetric fiber Bragg gratings (AFBGs) written in step-index fiber and vortex fiber, respectively. The mode coupling properties of AFBGs are numerically investigated. Compared to step-index fiber, the large mode separation in the vortex fiber is beneficial to extracting the desired vector mode at specific wavelengths. In addition, the polarization of incident light and the attenuation coefficient of index change distribution of the AFBG play critical roles in the mode coupling process. The proposed AFBG provides an efficient method to realize high-order vector mode conversion, and it shows great potential for orbital angular momentum multiplexing and fiber lasers with vortex beam output.
我们提出了一种基于分别写入阶跃折射率光纤和涡旋光纤中的非对称光纤布拉格光栅（AFBG）的矢量模式转换方法。对AFBG的模式耦合特性进行了数值研究。与阶跃折射率光纤相比，涡旋光纤中的大模式间隔有利于在特定波长下提取所需的矢量模式。此外，入射光的偏振和AFBG折射率变化分布的衰减系数在模式耦合过程中起着关键作用。所提出的AFBG为实现高阶矢量模式转换提供了一种有效方法，并且在轨道角动量复用和具有涡旋光束输出的光纤激光器方面显示出巨大潜力。
