Spatiotemporal vortex pulses (STVPs) with transverse orbital angular momentum (OAM) have recently stimulated great interest, influencing wide disciplines from classical to quantum optics. However, generating sophisticated STVPs in high‐efficiency and compact systems remains a challenge. This work outlines an ultra‐compact metasurface approach to efficiently generate STVPs through the coupling of free‐space plane waves with a quasi‐bound state in the continuum (quasi‐BIC). The approach leverages external excitation of the quasi‐BIC at the Γ‐point by slightly dislocating two sub‐layer gratings to break the mirror symmetries. This operation converts the incident wave into a unidirectional surface mode and induces a Fano resonance, resulting in STVPs in the frequency‐momentum domain. The method is demonstrated experimentally with a meta‐grating to produce an electromagnetic (EM) STVP with a topological charge of l = −1 with high fidelity and use the set‐up to unravel the hitherto unexplored diffraction and dispersive properties of near‐field STVPs. The present work can be extended from the microwave to the visible light regime by simply scaling the metasurface, and allowing high‐order OAM generation through cascaded elements, thereby paving a robust way to build up ultra‐compact STVP multiplexing devices for future applications.

中文翻译：

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位错双层金属光栅上连续体中的准束态用于时空涡旋脉冲的产生


具有横向轨道角动量 （OAM） 的时空涡旋脉冲 （STVP） 最近引起了人们的极大兴趣，影响了从经典光学到量子光学的广泛学科。然而，在高效和紧凑的系统中生产复杂的 STVP 仍然是一个挑战。这项工作概述了一种超致密超表面方法，通过自由空间平面波与连续体中的准束缚态 （quasi-BIC） 的耦合来有效生成 STVP。该方法利用准 BIC 在 Γ 点的外部激励，通过稍微错位两个子层光栅来打破反射镜对称性。该操作将入射波转换为单向表面模式并感应 Fano 共振，从而在频动量域中产生 STVP。该方法通过实验证明，使用超光栅产生拓扑电荷为 l = -1 且具有高保真度的电磁 （EM） STVP，并使用该装置来揭示近场 STVP 迄今为止未被探索的衍射和色散特性。通过简单地缩放超表面，并允许通过级联元件生成高阶 OAM，目前的工作可以从微波扩展到可见光领域，从而为构建超紧凑的 STVP 多路复用器件铺平了一条稳健的道路，用于未来的应用。