Abstract
An equivalent circuit model (ECM) using a MATLAB code to analyze a tunable two-layered graphene-based chiral dual-function metamirror, is proposed in this work. The investigated metastructure is composed of complementary U-shaped graphene resonator arrays in the terahertz (THz) region. The ECM analysis could be used for any two-layered chiral metastructure for any frequencies, containing resonators with a thickness less than λ/50. The characteristics of the proposed tunable metamirror were analyzed numerically using the finite element method (FEM) in CST Software to verify the ECM analysis. The proposed metamirror can be used in polarization-sensitive devices in the THz region with simpler biasing without a need for ion gels or similar. It works as a broadband TE and multiband (four bands) TM mirror in the 0.3–4.5 THz bandwidth with a strong linear dichroism (LD) response (up to 96%). The designed mirror is a dynamically tunable, dual-functional structure, requiring only 90° rotation of the incident electromagnetic fields to switch between broadband and multiband spectral behavior making it a promising candidate for future THz intelligent systems. The proposed ECM is in agreement with the FEM results. The ECM analysis provides a simple, fast, and effective way to understand the metamirror’s behavior and guides for the design and analysis of graphene-based chiral metastructures in the THz region.
Highlights
Chiral structures do not coincide with their mirror images
Analysis and optimization of this metastructure with graphene-based complementary resonator arrays in THz region, their performance in tunable metamirror applications was investigated in this work
In contrast to the chiral metastructure composed of common single-layered graphene-based U-shaped patterns28, we developed a chiral metamirror consisting of two-layered complementary U-shaped, 90° rotated, patterns
Summary
Numerical simulations were done using the finite element method (FEM) in the frequency domain solver of CST 20184,42. The positive real parts of the equivalent conductivities indicate the origin of loss, representing the resistive nature of the patterned graphene layers. The resonance frequencies of the absorber increase, which tends to exhibit a blueshift This is because the real part of the β in Eq [2] decreases as the μc increases. The structure acts as a broadband and multiband metamirror respectively for TE and TM incident electromagnetic waves in the 0.3–4.5 THz frequency region
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