物理学进展

物理学进展 ›› 2025, Vol. 45 ›› Issue (4): 191-168.doi: 10.13725/j.cnki.pip.2025.04.001

• •    

非线性光子晶体中二次谐波光学涡旋的产生与优化

刘世强 1，张鑫宇 1，陈 琰 2，李世凤 1，赵 刚 1，祝世宁 1，胡小鹏 1   

  1. 1. 固体微结构物理国家重点实验室，南京大学现代工程与应用科学学院，南京大学物理学院，南京 210093; 2. 光场调控科学与技术国家重点实验室，成都 610209
  • 出版日期:2025-08-20 发布日期:2025-09-28
  • 基金资助:
    国家自然科学基金 (Nos. 12192251, 12174185, 92163216, and 62288101). 

Optimizing the generation of second harmonic optical vortices from nonlinear photonic crystals 

LIU Shiqiang 1 , ZHANG Xinyu 1 , CHEN Yan 2 , LI Shifeng 1 , ZHAO Gang 1 , ZHU Shining 1 , HU Xiaopeng 1   

  1. 1. National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, and School of Physics, Nanjing University, Nanjing 210093, China; 2. National Key Laboratory of Optical Field Manipulation Science and Technology, Chengdu 610209, China 
  • Online:2025-08-20 Published:2025-09-28
  • Supported by:

PDF (PC)

10

摘要：

二阶非线性系数空间调制的非线性光子晶体 (NPC) 可以用于产生光学涡旋，从而拓展涡 旋光束的工作波长与拓扑荷数，为众多应用提供了新方法。在本工作中，我们研究了基模高斯光 束在非线性叉形光栅中非线性倍频产生的二次谐波 (SH) 涡旋光束的过程。分析了不同结构拓扑 荷和衍射级次下，远场 SH 光束的强度分布、位相分布及轨道角动量 (OAM) 谱。结果表明，当 衍射阶次和结构拓扑荷增大时，SH 光束呈现出角向干涉条纹和非均匀强度分布，偏离标准涡旋光 束的环形特性。为优化 SH 涡旋光束质量，进一步研究了基波光束腰半径、晶体厚度及光栅占空 比对倍频光场的影响。结果显示，增大基波光束腰半径、优化叉形光栅的厚度及占空比可有效抑 制不同衍射阶次间的干涉，从而改善 SH 光束质量。本研究为基于 NPC 的非线性光学器件性能 优化提供了理论指导。

关键词: optical vortex, nonlinear photonic crystal, second harmonic generation, orbital angular momentum

Abstract:

The generation of optical vortices from nonlinear photonic crystals (NPCs) with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex beams for various applications. In this work, the second harmonic (SH) optical vortex beams generated from nonlinear fork gratings under Gaussian beam illumination are numerically investigated. The far-field intensity and phase distributions, as well as the orbital angular momentum (OAM) spectra of the SH beams, are analyzed for different structural topological charges and diffraction orders. Results reveal that higher-order diffraction and larger structural topological charges lead to angular interference patterns and non-uniform intensity distributions, deviating from the standard vortex profile. To optimize the SH vortex quality, the effects of the fundamental wave beam waist, crystal thickness, and grating duty cycle are explored. It is shown that increasing the beam waist can effectively suppress diffraction order interference and improve the beam’s quality. This study provides theoretical guidance for enhancing the performance of nonlinear optical devices based on NPCs.

中图分类号: