# Infrared Metasurface with a Top Cross-Square Nanobrick Array for Realizing a Highly Efficient Lightwave Absorption Across a Broad Wavelength Region

## TL;DR

This paper introduces a metasurface design that efficiently absorbs infrared light across a wide wavelength range using a cross-square nanobrick array.

## Contribution

The novel contribution is a metasurface with a cross-square nanobrick array achieving high IR absorption efficiency over multiple atmospheric windows.

## Key findings

- The metasurface achieves over 86% average radiation absorptivity in the 1.28–14 μm wavelength region.
- It demonstrates less than 2% transmittance and maintains over 80% absorptivity at a 40° oblique incidence.
- The design utilizes electromagnetic shielding and resonant near-field excitation for efficient absorption.

## Abstract

A type of metasurface with a top cross-square nanobrick (CSNB) array is proposed for realizing a highly efficient infrared (IR) radiation absorption across a broad wavelength region covering three traditional atmospheric windows. The metasurface is successfully constructed by integrating a layered CSNB array over a composite dielectric bottom supported by a common silicon substrate. The metasurface sample experimentally exhibits an average radiation absorptivity of more than 86% and a very low transmittance of less than 2% in the 1.28–14 μm wavelength region measured. A polarized absorption sensibility of the incident lightwaves and an average IR absorptivity of more than 80% with an oblique incidence at 40° are also demonstrated. The strong broad IR absorption with a negligible radiation transmission can be attributed to the existence of an obvious electromagnetic shielding action of the nanocavity formed between adjacent titanium films, and further, the near-field lightwave excitation upon the CSNBs of the metasurface charged by incident lightwaves satisfying the resonant condition needed.