Open AccessBi-functional tunable reflector/high-Q absorber design using VO2 assisted graphene-coated cylinder array
Author(s) -
Shiva Hayati Raad,
Zahra Atlasbaf
Publication year - 2021
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.423129
Subject(s) - materials science , figure of merit , optics , refractive index , graphene , plasmon , optoelectronics , fano resonance , distributed bragg reflector , metamaterial , reflection coefficient , grating , reflector (photography) , nanotechnology , physics , wavelength , light source
In this paper, a bi-functional tunable reflector/absorber device using an assembly of graphene-coated cylindrical wires, backed by a thermally controlled phase change material, is proposed. The reflection coefficient of the graphene-coated wire-grating manifests multiple resonances, originating from the hybridized excitation of localized surface plasmons in the graphene shells. The first plasmonic resonance (with the order of two), in the free-standing configuration, shows tunable near-perfect reflection while the second plasmonic resonance (with the order of three), in the reflector-backed array, exhibits near-perfect absorption. Because of the metal-insulator transition in the phase change material, it is feasible to switch between these two functionalities using a VO 2 back layer. Moreover, the high-quality factor of the absorption band (Q ∼ 128.86) is due to its Fano line shape, leading to a narrow bandwidth. Thus, the absorbing mode can be possibly used for refractive index sensing with the sensitivity of S ∼ 9000 nm/RIU (refractive index unit) and figure of merit of FOM ∼ 104 RIU -1 . In the proposed structure, different optical, material, and geometrical parameters affect the optical response of the operating bands, offering a flexible design.