Localized spoof surface plasmons (LSSPs) have recently emerged as a new research frontier due to their unique properties and increasing applications. Despite the importance, most of the current researches only focus on electric/magnetic LSSPs. Very recent research has revealed that toroidal LSSPs, LSSPs modes with multipole toroidal moments, can be achieved at a point defect in a 2D groove metal array. However, this metamaterial shows the limitations of large volume and poor compatibility to photonic integrated circuits. To overcome the above challenges, here it is proposed and experimentally demonstrated compact planar metadisks based on split ring resonators to support the toroidal LSSPs at microwave frequencies. Additionally, it is experimentally demonstrated that the toroidal LSSPs resonance is very sensitive to the structure changes and the background medium. These might facilitate its utilization in the design and application of plasmonic deformation sensors and the refractive index sensors.

中文翻译：

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紧凑型元磁盘上的环形局域性欺骗等离子

本地化的欺骗表面等离激元（LSSP）由于其独特的性能和不断增加的应用，最近已成为新的研究前沿。尽管具有重要性，但当前的大多数研究仅集中于电磁LSSP。最近的研究表明，环形LSSP（具有多极环矩的LSSPs模式）可以在2D凹槽金属阵列中的点缺陷处实现。然而，这种超材料显示出大体积和与光子集成电路的兼容性差的局限性。为了克服上述挑战，在此提出并实验证明了基于裂环谐振器的紧凑平面元盘，以在微波频率下支持环形LSSP。此外，实验证明，环形LSSPs共振对结构变化和背景介质非常敏感。这些可能有助于其在等离子体变形传感器和折射率传感器的设计和应用中的利用。