We demonstrate that when a charged particle moves on top of a metal-slot metasurface consisting of metallic slot resonators, strong Smith–Purcell electromagnetic (EM) radiation can be produced at resonant frequency. By adjusting the period of the metasurface, the resonant (or working) frequency can be tuned from gigahertz to terahertz and infrared regions. Since the EM field is localized in the slots rather than at the metal surface, the metasurfaces are found to exhibit a very low absorption loss ratio ($<1\%$) in low working frequencies ($<1\mathrm{THz}$). Although it becomes larger in high frequencies ($>1\mathrm{THz}$), the loss ratio remains relatively low ($<12\%$). In addition, a nonlinear relationship is also uncovered between the resonant frequency and the reciprocal of the period. Our results could benefit the construction of efficient, compact terahertz, and infrared free-electron light sources.

中文翻译：

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金属槽超表面的有效太赫兹和红外史密斯-珀塞尔辐射

我们证明，当带电粒子在由金属缝隙谐振器组成的金属缝隙超表面上移动时，可以在谐振频率处产生强的Smith-Purcell电磁（EM）辐射。通过调整超颖表面的周期，可以将共振（或工作）频率从千兆赫调至太赫兹和红外区域。由于EM场位于槽中而不是金属表面上，因此发现超颖表面表现出非常低的吸收损耗比（$<\mathrm{1个}％$）在低工作频率（$<\mathrm{1个}\mathrm{太赫兹}$）。尽管在高频下会变大（$>\mathrm{1个}\mathrm{太赫兹}$），损失率仍然相对较低（$<12％$）。另外，在谐振频率和周期的倒数之间也发现非线性关系。我们的结果可能有益于构建高效，紧凑的太赫兹和红外自由电子光源。