Lin Qinggang, Zheng Shuiqin, Song Qiying, Zeng Xuanke, Cai Yi, Li Ying, Chen Zhenkuan, Zha Lang, Pan Xinjian, Xu Shixiang
Opt Lett. 2019 Feb 15;44(4):887-890. doi: 10.1364/OL.44.000887.
Converting a Gaussian mode to a vortex beam is much more inconvenient in the terahertz (THz) region than in the near-infrared (NIR) region due to underdevelopment of THz components and strong THz diffraction. This Letter reports the direct generation of THz vortex pulses by optical difference-frequency between two NIR chirped pulses with different topological charges (TCs). By designing a passive and transmissive device for a collinear NIR pulse pair with conjugated TCs, we have experimentally obtained stable THz vortex pulses with a TC value of 2 or -2. The process needs no THz components and so is flexible to be realized and has promising applications in the THz field.
由于太赫兹（THz）组件发展不完善以及太赫兹强烈的衍射现象，在太赫兹区域将高斯模式转换为涡旋光束比在近红外（NIR）区域要麻烦得多。本文报道了通过两个具有不同拓扑电荷（TC）的近红外啁啾脉冲之间的光学差频直接产生太赫兹涡旋脉冲。通过为具有共轭拓扑电荷的共线近红外脉冲对设计一个无源透射装置，我们通过实验获得了拓扑电荷值为2或 -2的稳定太赫兹涡旋脉冲。该过程无需太赫兹组件，因此易于实现且在太赫兹领域具有广阔的应用前景。
