Abstract
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.
Highlights
Metasurfaces, as an important branch of optical metamaterials, are two-dimensional (2D) array architectures which are formed by sub-wavelength periodic plasmonic nanostructure consisting of patterned dielectric and metal materials [1, 2]
In conclusion, a simple design of the triple-band perfect light absorber (PLA) based on hybrid metasurface has been proposed and investigated numerically in this work, which can be believed to be applicable for refractive index (RI) sensing
The proposed PLA based on the hybrid metasurface is designed to be only consisted of periodic arrays of silicon cross nanostructures deposited on a gold substrate
Summary
Metasurfaces, as an important branch of optical metamaterials, are two-dimensional (2D) array architectures which are formed by sub-wavelength periodic plasmonic nanostructure consisting of patterned dielectric and metal materials [1, 2]. It has been confirmed that the absorption capacity of PLA is usually depended on the shape, size, thickness, and composition of the plasmonic metasurface, which are sensitive to the refractive index (RI) of surrounding material [29,30,31,32,33,34,35,36]. As it is well known for sensing applications, the narrowband PLA was investigated intensively due to its large
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