Temporally modulated metamaterial based on a multilayer graphene structure

Abstract

The recently developed concept of time-varying metamaterials paves the way for advanced methods of electromagnetic property modulation, such as magnet-free isolators, frequency converters, and other nonreciprocal photonic components. Here, we analyze the metamaterial based on the periodically arranged temporally modulated graphene layers via a steplike graphene Fermi level. The material properties are described by the effective medium theory. The electromagnetic wave temporal scattering phenomenon caused by rapid steplike graphene Fermi level switching is considered. It is demonstrated that the frequency of scattered waves increases as the Fermi level grows rapidly and vice versa. The relation between the amplitudes of forward-and backward-scattered waves is found using the Laplace transform technique. The proposed concept allows us to efficiently generate frequency harmonics under instant switching of the graphene Fermi level at a few meV. Our investigation provides a basement for the realization of temporally modulated multilayer structures based on functional tunable materials as power-efficient frequency converters.

Polarization conversion and lateral shifts in multilayered structure with finitely-gapped topological surface states

“…The adoption of topological materials, such as graphene and TI, in periodic multilayered structure has been recently investigated. The applicabilities of graphene multilayers for frequency conversion and electromagnetic wave absorption have been studied [22,23], and it is also found that the TI effects can be accumulated in multilayered structures [24]. High Chern number phase behavior [25] and tunable spontaneous emission interference [26,27] can be achieved in the TI multilayers.…”

Terahertz tunable three-dimensional photonic jets

“…Optical characteristics of PNJs and TJs are governed by the index of refraction, geometry, and size of the generating micro-object 52 – 55 as well as the refractive index of the material around the micro-object 56 and properties of the incident light 2 , 57 . Refractive index can be modulated through incorporation of core–shell geometries 58 , 59 , liquid crystals 60 , 61 , temperature-sensitive vanadium oxide (VO 2 ) coating 62 , and graphene coating 63 , 64 in dielectric micro-objects in order to produce tunable PNJs and TJs. Although these approaches allow dynamic control of the refractive index, they are associated with their own features and principles of operation, for example slow response time (typically on the order of milliseconds) in liquid crystals 65 , control by precise change in the temperature in VO 2 (a phase change material), and the need to fabricate graphene with single-atom-layer thickness.…”

Ultra-broadband THz absorbers based on 3D graphene

“…Previous approaches have involved mostly metamaterials exhibiting antireflective properties and absorption resonances (thus narrow-band operation) [12][13][14][15]. Some of the proposed metamaterials structures have also featured multilayer graphene sheets [16][17][18]. High-porosity three-dimensional (3D) graphene materials have been demonstrated to exhibit excellent wide-angle absorbing properties in the range below 1 THz [19].…”