飞秒激光写入的光纤布拉格光栅中高纯度光学涡旋的产生。

High purity optical vortex generation in a fiber Bragg grating inscribed by a femtosecond laser.

作者信息

Li Yali, Bai Zhiyong, Liu Zhao, Zhu Guoxuan, Yang Kaiming, Yu Jian, Chen Jiayan, Fu Cailing, Liao Changrui, Wang Yiping

出版信息

Opt Lett. 2020 Dec 15;45(24):6679-6682. doi: 10.1364/OL.410277.

Abstract

In this Letter, a method for orbital angular momentum (OAM) mode generation is proposed and experimentally demonstrated using a fiber Bragg grating (FBG) and off-axis incidence. The FBG fabricated by a femtosecond laser was used to couple the incidence beam into backward high-order modes. The generated modes were then reformed into ring-shaped OAM modes by adjusting the off-axis displacement of the input beam. The intensity distribution, phase vortex, and mode purity of the output light were experimentally investigated. Results indicates that the order of the generated OAM modes is dependent on the resonant wavelength of the FBG, and the sign of the OAM topological charge is determined by the displacement value of the off-axis incident light. In the experiment, ±1- and ±2-order OAM modes were achieved and confirmed, with purities as high as 90%, 91%, 89%, and 88%, respectively.

摘要

在本信函中，提出了一种利用光纤布拉格光栅（FBG）和离轴入射产生轨道角动量（OAM）模式的方法，并进行了实验验证。用飞秒激光制备的FBG将入射光束耦合到反向高阶模式中。然后，通过调整输入光束的离轴位移，将产生的模式重新整形为环形OAM模式。对输出光的强度分布、相位涡旋和模式纯度进行了实验研究。结果表明，产生的OAM模式的阶数取决于FBG的谐振波长，OAM拓扑电荷的符号由离轴入射光的位移值决定。在实验中，实现并确认了±1和±2阶OAM模式，纯度分别高达90%、91%、89%和88%。