Opt Lett. 2018 Aug 15;43(16):3858-3861. doi: 10.1364/OL.43.003858.
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 THz). Although it becomes larger in high frequencies (>1 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.
我们证明了当一个带电粒子在由金属槽谐振器组成的金属槽超表面上运动时，在共振频率下可以产生很强的史密斯-珀塞尔电磁（EM）辐射。通过调整超表面的周期，可以将共振（或工作）频率从吉赫兹调谐到太赫兹和红外区域。由于 EM 场位于槽中而不是金属表面，因此发现超表面在低工作频率（<1 THz）下表现出非常低的吸收损耗比（<1%）。尽管在高频（>1 THz）时损耗比变大，但仍相对较低（<12%）。此外，还揭示了共振频率与周期倒数之间的非线性关系。我们的结果可能有利于构建高效、紧凑的太赫兹和红外自由电子光源。
