Opt Express. 2023 May 8;31(10):16267-16280. doi: 10.1364/OE.484588.
Optical vortices with longitudinal orbital angular momentum (OAM) as a powerful tool for particle control, imaging and communication have been greatly developed. We introduce a novel property of broadband terahertz (THz) pulse, represented by frequency-dependent OAM orientation in spatiotemporal domain with transverse and longitudinal OAM projection. We illustrate a frequency-dependent broadband THz spatiotemporal optical vortex (STOV) in plasma-based THz emission driven by cylindrical symmetry broken two-color vortex field. We detect the evolution of OAM by time-delayed 2D electro-optic sampling combined with Fourier transform. This THz optical vortices tunability in spatiotemporal domain expands a new way for studying STOV and plasma-based THz radiation.
具有纵向轨道角动量（OAM）的光学涡旋作为一种强大的粒子控制、成像和通信工具得到了极大的发展。我们介绍了一种新的宽带太赫兹（THz）脉冲特性，它在时空域中表现为与横向和纵向 OAM 投影相关的频率相关 OAM 方向。我们在由圆柱对称性破坏的双色涡旋场驱动的基于等离子体的太赫兹发射中，说明了宽带太赫兹时空光涡旋（STOV）的频率相关特性。我们通过结合二维电光取样和傅里叶变换的时间延迟来检测 OAM 的演化。这种时空域中太赫兹光学涡旋的可调谐性为研究 STOV 和基于等离子体的太赫兹辐射开辟了一条新途径。
