We propose a terahertz surface plasmon resonance sensor based on dielectric metagrating coupling to the spoof surface plasmon (SSP) mode on periodically grooved metal films. The well-designed silicon metagrating converts the normal incident to the necessary angle in the dielectric substrate exciting SSP with the transmission coupling between couplers and SSP metasurfaces. Using an all-dielectric metagrating as an external coupler, the tightly confined SSP mode can be excited within a small resonant cavity, causing the strong light–matter interaction. The proposed SSP dielectric meta-couplers will pave new routes for ultra-thin and compact sensing devices. The dielectric substrate thickness, the air gap distance between the substrate and the metal groove array, and metal groove gaps have remarkable influences on the characteristics of SSP sensing. The SSP sensing by metagrating coupling with the resonance frequency around 0.404 THz provides a high sensitivity of up to 335 GHz/RIU and a detection limit less than 0.0001 RIU with a frequency resolution of 33.5 MHz. Dielectric metagrating coupling SSP provides enormous potential for constructing ultra-sensitive and compact SSP sensors in the terahertz frequency region.

中文翻译：

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基于介电元光栅耦合的太赫兹欺骗表面等离子体传感

我们提出了一种基于介电迁移耦合到周期性开槽的金属膜上的欺骗表面等离子体激元（SSP）模式的太赫兹表面等离子体激元共振传感器。精心设计的硅超光栅将电介质基板中的法向入射转换为必要的角度，通过耦合器和 SSP 超表面之间的传输耦合激发 SSP。使用全介电元光栅作为外部耦合器，可以在一个小的谐振腔内激发紧密限制的 SSP 模式，从而引起强烈的光-物质相互作用。拟议的 SSP 介电元耦合器将为超薄和紧凑的传感设备铺平新的路线。介质基板厚度、基板与金属凹槽阵列之间的气隙距离以及金属凹槽间隙对 SSP 传感特性有显着影响。通过与 0.404 THz 左右的谐振频率进行元光栅耦合的 SSP 传感提供高达 335 GHz/RIU 的高灵敏度和小于 0.0001 RIU 的检测限，频率分辨率为 33.5 MHz。介电元光栅耦合 SSP 为构建太赫兹频率区域的超灵敏和紧凑 SSP 传感器提供了巨大的潜力。