Broadband Perfect Optical Absorption by Coupled Semiconductor Resonator-Based All-Dielectric Metasurface.

Zhi Weng,Yunsheng Guo

doi:10.3390/ma12081221

Abstract

Resonance absorption mechanism-based metasurface absorbers can realize perfect optical absorption. Further, all-dielectric metasurface absorbers have more extensive applicability than metasurface absorbers that contain metal components. However, the absorption peaks of the all-dielectric metasurface absorbers reported to date are very sharp. In this work, we propose a broadband optical absorption all-dielectric metasurface, where a unit cell of this metasurface is composed of two coupled subwavelength semiconductor resonators arrayed in the direction of the wave vector and embedded in a low-index material. The results indicate that the peak absorption for more than 99% is achieved across a 60 nm bandwidth in the short-wavelength infrared region. This absorption bandwidth is three times that of a metasurface based on the conventional design scheme that consists of only a single layer of semiconductor resonators. Additionally, the coupled semiconductor resonator-based all-dielectric metasurface shows robust perfect absorption properties when the geometrical and material parameters—including the diameter, height, permittivity, and loss tangent of the resonator and the vertical and horizontal distances between the two centers of the coupled resonators—are varied over a wide range. With the convenience of use of existing semiconductor technologies in micro/nano-processing of the surface, this proposed broadband absorption all-dielectric metasurface offers a path toward realizing potential applications in numerous optical devices.

Highlights

Optical absorption is a typical problem in light-matter interactions
Numerous experiments have demonstrated that the subwavelength high-index particles that are used as unit cells can be used to construct all-dielectric metasurfaces that operate in the microwave [24,25] and THz [26,27] bands but in the infrared [28,29] and visible [30,31] bands
It is known that most of the incident electromagnetic waves are concentrated in the particles in the resonant state [32], which means that a moderate dielectric loss can completely dissipate the strongly localized electromagnetic energy in the particles and zero transmittance can be achieved

Summary

Introduction

Optical absorption is a typical problem in light-matter interactions. Strengthening and controlling optical absorption has long been a significant research topic in the fields of optics and optoelectronics.Perfect light absorption, which implies zero reflection, zero transmission, and maximum absorption, has many potential applications in devices such as absorbers [1,2,3,4], sensors [5,6,7], photodetectors [8,9], thermal emitters [10,11], and energy harvesting devices [12,13,14,15]. When parameters such as the height, diameter, permittivity, and loss tangent of the two coupled resonators and the vertical and horizontal distances between them are varied over a wide range, the unit cell still demonstrates robust and perfect wideband absorption features.

Results

Conclusion