Actively tunable linear and circular dichroic metamirrors based on single-layer graphene

Abstract

Aiming at the problems of low efficiency, single function and complex structure of the existing dichroic metamirrors, the actively tunable linear and circular dichroic metamirrors based on single-layer graphene are proposed in this study. The designed metamirrors are mainly composed of the ion-gel, patterned graphene, polyimide, polysilicon and gold substrates. The anisotropy of the achiral structures can be used to realize circular dichroism (0.8) and linear dichroism (0.9) in two directions at the same time without functional switching. Additionally, the incidence angle of electromagnetic waves, rather than the structural chirality, is used to create the exceptionally strong dichroism. The proposed metamirrors not only increase the integration, but also reduce the angular dispersion and complexity of the structure. What's more, by changing the Fermi level of graphene, the CD function of the metamirrors can be tuned in the range of 0 - 0.8, and the LD function can be tuned in the range of 0.22 - 0.9. The designed metamirrors can achieve dual functions under a wide range of incident angles, and can be widely used in various fields such as terahertz imaging, biological detection, optical sensing, and spectrometry.

Terahertz graphene-based multi-functional anisotropic metamaterial and its equivalent circuit model

“…absorption/reflection (%) Max. LD/CD/CCD response/(%) Multi-functional 7 Yes 0.5–4.5 THz Yes 99 (absorption) LD/94 Single-functional 8 Yes 0.3–4.5 THz Yes 99 (reflection) LD/96 Dual-functional 10 Yes 1–5.5 THz Yes 100 (absorption) LD/99 Single-functional 11 Yes 2–4.5 THz No 100 (absorption) CD/86.3 Dual-functional 12 Yes 0.5–1.5 THz No 100 (absorption) CD/80 LD/90 Dual-functional 31 No 7–10 GHz No 93.2 (absorption) CD/86 Single-functional 32 No 375–500 THz No 80 (absorption) CD/50 Single-functional 33 No 187.5–375 THz No 50 (absorption) CD/12 …”

“…Graphene-based chiral and anisotropic metamaterials have been proposed, analyzed, and investigated recently. They produce tunable CD (CD = CD chi + CD ani ) and/or LD responses up to 99% 3 – 12 . The design and investigation of tunable graphene-based metamaterials for switching, inverting, modulating, sensing, and so on applications is a worthy and uninvestigated field of research.…”

“…The recently reported Graphene-based chiral and anisotropic metamaterials 3 – 12 have one to four bands. Except for Ref.…”

Numerical Simulation and Equivalent Circuit Model of Multi-Band Terahertz Absorber Composed of Double-Sided Graphene Comb Resonator Array

“…Metamaterials consisting of single or multi-layer of resonator arrays and having non-symmetrical geometries with the possibility to superimpose on their mirror image by the degrees of rotation have attracted broad attention for their features [1][2][3][4][5][6]. This type of metamaterials has shown a capability to produce chirality responses such as circular dichroism (CD) [7][8][9][10] or linear dichroism (LD) [10][11][12].…”

“…This type of metamaterials has shown a capability to produce chirality responses such as circular dichroism (CD) [7][8][9][10] or linear dichroism (LD) [10][11][12]. Metamaterials with non-symmetrical geometries have been designed and proposed for different applications such as absorbers [8,12,13], biosensors [14,15], converters [16,17], switches [18,19], and mirrors [6,20] recently showing their versatile possibilities in various the fields of science.…”