美国印第安纳大学Chen-Ting Liao团队研究了高谐波产生的极紫外时空涡旋。2025年6月11日出版的《自然—光子学》杂志发表了这项成果。
时空光学涡旋（STOV）是一种时空结构光脉冲，具有独特的拓扑结构，将空间和时间域耦合起来，并携带横向轨道角动量（OAM）。到目前为止，它们的生成仅限于光谱的可见光和红外区域。在过去的十年中，研究表明，通过高次谐波的产生过程，可以将携带纵向OAM的空间光学涡旋从近红外上转换为极紫外（EUV），从而产生具有不同飞秒和阿秒结构的涡旋。
研究组从理论和实验上证明了使用近红外STOV驱动激光脉冲产生EUV时空和空间光谱涡旋。他们使用聚焦STOV的解析表达式来进行高次谐波产生的宏观计算，并将其与实验结果进行直接比较。由于STOV光束不是本征传播模，研究组在近场和远场中对高电荷EUV STOV进行了表征，以表明它们代表了共轭时空和空间光谱涡旋对。该工作提供了在纳米/阿秒尺度域拓扑耦合的高频光束，具有横向OAM，适用于探索磁性材料、手性介质和纳米结构中的电子动力学。
附：英文原文
Title: Extreme-ultraviolet spatiotemporal vortices via high harmonic generation
Author: Martn-Hernndez, Rodrigo, Gui, Guan, Plaja, Luis, Kapteyn, Henry C., Murnane, Margaret M., Liao, Chen-Ting, Porras, Miguel A., Hernndez-Garca, Carlos
Issue&Volume: 2025-06-11
Abstract: Spatiotemporal optical vortices (STOVs) are space–time structured light pulses with a unique topology that couples spatial and temporal domains and carry transverse orbital angular momentum (OAM). Up to now, their generation has been limited to the visible and infrared regions of the spectrum. During the last decade, it was shown that through the process of high-order harmonic generation, it is possible to upconvert spatial optical vortices that carry longitudinal OAM from the near-infrared into the extreme-ultraviolet (EUV), thereby producing vortices with distinct femtosecond and attosecond structure. In this work, we demonstrate theoretically and experimentally the generation of EUV spatiotemporal and spatiospectral vortices using near-infrared STOV driving laser pulses. We use analytical expressions for focused STOVs to perform macroscopic calculations of high-order harmonic generation that are directly compared to the experimental results. As STOV beams are not eigenmodes of propagation, we characterize the highly charged EUV STOVs in both the near and far fields to show that they represent conjugated spatiotemporal and spatiospectral vortex pairs. Our work provides high-frequency light beams topologically coupled at the nanometre/attosecond scales domains with transverse OAM that could be suitable to explore electronic dynamics in magnetic materials, chiral media and nanostructures.
DOI: 10.1038/s41566-025-01699-w
Source: https://www.nature.com/articles/s41566-025-01699-w