Broadband perfect transparency-to-absorption switching in tilted anisotropic metamaterials based on the anomalous Brewster effect

Abstract

Dynamically switchable light transmission/absorption functionality is highly desirable in sensing and functional devices. However, the operating bandwidth of the newly emerging schemes using resonant meta-structures is inherently limited. In this work, we design and numerically demonstrate a non-resonant tilted anisotropic metamaterial consisting of phase-change materials. When the phase transition of the phase-change material from amorphous phase to crystalline phase occurs, the functionality of the metamaterial can be switched from perfect transparency to perfect absorption for transverse-magnetic polarization under oblique incidence over a broad spectrum. Such a remarkable phenomenon originates in the anomalous Brewster effect, which enables broadband reflectionless transmission/absorption of light under the anomalous Brewster’s angle. Moreover, gradient metamaterials exhibiting dynamically controllable functionality for incident light with an almost arbitrary wavefront are demonstrated. The proposed metamaterials are simple but highly efficient, which may find applications in sensing and advanced and intelligent optical devices.

Recent developments in Chalcogenide phase change material-based nanophotonics

“…Recent nanophotonics inverse design reports have been increasingly resorting to learning-based approaches, where data-driven techniques like machine learning (ML) and Deep Learning (DL) assist the inverse design process. Several review articles [146][147][148][149][150][151][152][153][154][155][156] have extensively summarized the use of machine learning algorithms in nanophotonics. However, the implementation of all these algorithms in PCM-based nanophotonics still remains largely unexplored.…”

Supplementary document for Anomalous generalized Brewster effect and ultra-broadband reflectionless Brewster metasurfaces - 5982247.pdf

“…Second, we'd like compare with the newly proposed ABE. The ABE was proposed to obtain reflectionless absorption [6][7][8], which however, requires dielectric materials with infinitely large permittivity when the non-reflection angle approaches ± 90°, i.e. near grazing incidence.…”

“…near grazing incidence. This is because the anomalous Brewster's angle (ABA) is -𝜃 B =arctan 𝜀 𝑑 1 [6][7][8], where 𝜀 𝑑 1 is the relative permittivity of dielectric substrate [upper panel graph in Fig. S6(a)].…”