A simple design of triple-band perfect light absorber (PLA) based on hybrid metasurface in visible region has been presented in this work, which turns out to be applicable for refractive index (RI) sensing. Distinct from previous designs, the proposed hybrid metasurface for visible PLA is only consisted of periodic silicon cross nanostructure arrays and gold substrate. The periodic silicon cross arrays deposited on the gold substrate contribute to excite the guided modes under the normal incident light illumination. According to the simulation results, it can be found that three perfect absorption peaks of 98.1%, 98.7%, and 99.6% which are located at 402.5 THz, 429.5 THz, and 471.5 THz, respectively, have been clearly observed in PLA. This triple-band perfect absorption effect could be attributed to the intrinsic loss of silicon material originated from the guided mode excitations caused by the standing waves of different orders. It has been confirmed that the perfect absorption properties of the PLA can be easily regulated by changing the geometric parameters of the unit-cell nanostructure. Furthermore, the designed PLA served as a RI sensor can achieve sensitivity of about 25.3, 41.3, and 31.9 THz /refractive index unit (RIU). It can be believed that the proposed design of PLA for RI sensing would provide great potential applications in sensing, detecting, the enhanced visible spectroscopy, etc.

中文翻译：

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基于混合超表面的三波段完美光吸收器，用于传感应用。

这项工作提出了一种基于可见光区域混合超表面的三波段完美光吸收器（PLA）的简单设计，该设计适用于折射率（RI）传感。与之前的设计不同，所提出的可见光PLA混合超表面仅由周期性硅交叉纳米结构阵列和金基板组成。沉积在金基板上的周期性硅十字阵列有助于在法向入射光照射下激发导模。根据模拟结果可以发现，PLA中清晰地观察到了三个完美吸收峰，分别位于402.5 THz、429.5 THz和471.5 THz，分别为98.1%、98.7%和99.6%。这种三能带完美吸收效应可归因于硅材料的固有损耗，该损耗源自不同阶驻波引起的导模激励。已经证实，通过改变晶胞纳米结构的几何参数可以轻松调节PLA的完美吸收性能。此外，设计的 PLA 作为 RI 传感器可以实现约 25.3、41.3 和 31.9 THz/折射率单位 (RIU) 的灵敏度。可以相信，所提出的用于RI传感的PLA设计将在传感、检测、增强可见光谱等方面提供巨大的潜在应用。