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中国物理学会期刊

基于微米级全光磁全息结构的涡旋光生成实验研究

CSTR: 32037.14.aps.74.20250649

Experimental study on vortex beam generation based on micron-scale all-optical magnetic holographic structures

CSTR: 32037.14.aps.74.20250649
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  • 涡旋光因其携带轨道角动量(OAM), 在光通信、光学操控及精密测量等领域具有重要的应用价值. 现有的涡旋光生成方法(如螺旋相位板、空间光调制器和超表面)虽已广泛应用, 但仍存在结构固化、动态调控困难以及集成性不足等问题, 难以满足可重构、可编程涡旋光生成系统的应用需求. 为此, 本文提出一种基于全光磁全息的新型涡旋光生成方案. 该方法利用单脉冲飞秒激光将预先设计的叉形光栅全息图以打点方式写入微米级GdFeCo磁性材料表面, 并通过磁光法拉第衍射效应再现涡旋光. 实验结果表明, 通过一维叉形光栅可实现不同拓扑荷(l = ±2, ±5, ±8)的涡旋光生成, 且涡旋光半径与拓扑荷呈正相关; 二维叉形光栅则可生成多拓扑荷分布的3×3涡旋光阵列, 实现涡旋光的空间可控调制. 该方案具备可擦写重构、重复使用及高稳定性等优势, 为微/纳尺度下涡旋光的灵活调控与集成应用提供了新思路.

     

    In recent years, vortex beams carrying orbital angular momentum (OAM) have been widely applied to optical communications, optical manipulation, and precision measurement. However, traditional generation methods such as spiral phase plates, spatial light modulators, and metasurfaces, encounter several challenges, including structural rigidity, limited dynamic tunability, and inadequate integration capabilities. These limitations hinder the realization of reconfigurable and programmable vortex beam generation systems. In order to solve these problems, a novel vortex beam generation method based on all-optical magnetic holography is presented in this paper. In this technique, a single-pulse femtosecond laser is used in a dotted writing mode to engrave a pre-designed fork-shaped grating hologram onto the surface of a micron-scale magnetic material, GdFeCo. Under subsequent illumination with a plane wave, the vortex beam is reconstructed via the magneto-optical Faraday diffraction effect. Experimental results show that one-dimensional fork-shaped gratings can flexibly generate vortex beams with different topological charges (l = ±2, ±5, ±8), where the beam radius increases with the augment of topological charges. Furthermore, a two-dimensional fork-shaped grating, formed by superimposing horizontal and vertical one-dimensional gratings, can produce 3 × 3 vortex beam arrays with various topological charge distributions, enabling the spatial modulation of OAM. This method offers advantages such as reusability, long-term stability, and a compact structure, thus providing a programmable and reconfigurable platform for generating micro-structured vortex beams. Unlike traditional static optical elements, this approach enables dynamic, high-resolution, and easy-to-integrate solutions, and shows great application potential in OAM-based multi-channel optical communication, multi-particle manipulation, and parallel laser processing.

     

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