Tunable circular dichroism based on graphene-metal split ring resonators

Abstract

The chiroptical response of the chiral metasurface can be characterized by circular dichroism, which is defined as the absorption difference between left-handed circularly polarized incidence and right-handed circularly incidence. It can be applied in biology, chemistry, optoelectronics, etc. Here, we propose a dynamically tunable chiral metasurface structure, which is composed of two metal split-ring resonators and a graphene layer embedded in dielectric. The structure reflects right-handed circularly polarized waves and absorbs left-handed circularly polarized waves under normal incidence. The overall unit structural parameters of the chiral metasurface were discussed and analyzed, and the circular dichroism was 0.85 at 1.181 THz. Additionally, the digital imaging function can be realized based on the chiral metasurface structure, and the resolution of terahertz digital imaging can be dynamically tuned by changing the Fermi level of graphene. The proposed structure has potential applications in realizing tunable dynamic imaging and other communication fields.

Diatomic Metasurface for Efficient Six‐Channel Modulation of Jones Matrix

“…Optical metasurface, [ 6–11 ] which consists of planar meta‐atoms with specific order, has been proposed to provide a compact and efficient platform for complex manipulation of light waves. Various single‐layer optical metasurfaces have been presented to demonstrate independent modulation of multiple optical dimensions, fostering potential applications in ultra‐compact image displays, [ 12–16 ] high‐density optical storage, [ 17,18 ] optical anti‐counterfeiting, [ 19 ] and many other related fields. Tailoring the Jones matrix of the optical metasurface consists in addressing the complex reflection/transmission by varying the nanostructure geometries.…”

A switchable and tunable multifunctional terahertz polarization converter based on a graphene metasurface

“…In 2021, Zhang et al used two metal split-ring resonators with varying revolution angles and a graphene layer in the dielectric layer to couple with each other to generate the CD effect. 11 In 2022, a significant CD effect was achieved using a bilayer of twisted graphene chiral metamirrors. 4 Most of the designs above are single function metasurfaces.…”

Tunable circular dichroism based on chiral photonic crystals

“…18 They are widely used to adjust the polarization of electromagnetic waves on a sub-wavelength scale, contributing to significant advances in imaging display, encryption, quantum information, biosensors, and more. [19][20][21] Chiral nanostructures have been fabricated in various shapes, such as "I-shaped" resonators with asymmetric twisted metallic wires, 22 pairs of mutually twisted planar metal patterns, 23 two metal split-ring resonators, and a graphene layer embedded in dielectric, 24 spin-selective full-dimensional manipulation of optical waves with chiral mirror, 25 etc. 24,[26][27][28][29][30][31][32] Proper design of chiral dichroism selective structures is still a crucial way for applications.…”

“…They are widely used to adjust the polarization of electromagnetic waves on a sub-wavelength scale, contributing to significant advances in imaging display, encryption, quantum information, biosensors, and more 19 – 21 Chiral nanostructures have been fabricated in various shapes, such as “I-shaped” resonators with asymmetric twisted metallic wires, 22 pairs of mutually twisted planar metal patterns, 23 two metal split-ring resonators, and a graphene layer embedded in dielectric, 24 spin-selective full-dimensional manipulation of optical waves with chiral mirror, 25 etc 24 , 26 – 32 Proper design of chiral dichroism selective structures is still a crucial way for applications.…”