Efficient Generation of Microwave Plasmonic Vortices via a Single Deep‐Subwavelength Meta‐Particle
Efficient Generation of Microwave Plasmonic Vortices via a Single Deep‐Subwavelength Meta‐Particle
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DOI：
10.1002/lpor.201800010
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发表时间：
2018-06
影响因子：
11
通讯作者：
Hai Su;Xiaopeng Shen;Guangxu Su;Lin Li;Jianping Ding;Fanxin Liu;P. Zhan;Yongmin Liu;Zhenlin Wang
中科院分区：
文献类型：
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作者：
Hai Su;Xiaopeng Shen;Guangxu Su;Lin Li;Jianping Ding;Fanxin Liu;P. Zhan;Yongmin Liu;Zhenlin Wang
以光学涡旋形式携带轨道角动量（OAM）的光束由于其提供新的维度和方法来操纵光-物质相互作用的能力而引起了极大的兴趣。最近，等离子体提供了有效的方法来聚焦超过衍射极限的涡旋光束。然而，与可见光和近红外区域不同的是，在远红外甚至更长波长下实现等离子体涡旋仍然是一个巨大的挑战。提出了一种在低频区产生深亚波长近场电磁涡旋的有效方法。利用金属梳形波导支持的电磁场的非对称空间分布，可以激发强烈限制在具有所需拓扑电荷的精心设计的深亚波长Meta粒子中的等离子体涡旋模式。微波实验证实了这种独特的现象。一个等效的物理模型进行了支持的数值模拟，以揭示等离子体激元涡旋产生的基本机制。这种欺骗-等离子体激元辅助的EM波与OAM的聚焦可能会发现在微波，太赫兹，甚至远红外区域操作的功能集成元件和设备的潜力。
Light beams carrying orbital angular momentum (OAM) in the form of optical vortices have attracted great interest due to their capability for providing a new dimension and approach to manipulate light–matter interactions. Recently, plasmonics has offered efficient ways to focus vortex beams beyond the diffraction limit. However, unlike in the visible and near‐infrared regime, it is still a big challenge to realize plasmonic vortices at far‐infrared and even longer wavelengths. An effective strategy to create deep‐subwavelength near‐field electromagnetic (EM) vortices operating in the low frequency region is proposed. Taking advantage of the asymmetric spatial distribution of EM field supported by a metallic comb‐shaped waveguide, plasmonic vortex modes that are strongly confined in a well‐designed deep‐subwavelength meta‐particle with desired topological charges can be excited. Such unique phenomena are confirmed by the microwave experiments. An equivalent physical model backed up by the numerical simulations is performed to reveal the underlying mechanism of the plasmonic vortex generation. This spoof‐plasmon assisted focusing of EM waves with OAM may find potentials for functional integrated elements and devices operating in the microwave, terahertz, and even far‐infrared regions.