Magnetic Dipole and Magnetic Quadrupole Scattering Enhanced Graphene‐based Tunable Plasmonic Metasurface‐ Design and Sensor Applications

• Published in: Optik (Stuttgart) 2024-09, Vol.311, p.171947, Article 171947
• Main Author: Roy, Shuvajit
• Format: Article
• Language: English
• Subjects: Chemical solvent sensor; Dipole; Graphene; Metasurface; Plasmonic; Quadrupole
• ISSN: 0030-4026; 1618-1336
• DOI: 10.1016/j.ijleo.2024.171947

In this paper, we have proposed a graphene-based tunable plasmonic sensor in the far-infrared region. Our structure consists of patterned graphene disks on a SiO2 gap dielectric structure. On a SiO2 substrate, a monolayer of graphene is placed. On top of that, with a gap dielectric structure, graphene is disk patterned, forming a 2D metastructure. At the resonance wavelength where the dominating electric dipole due to plasmonic resonance is suppressed, the scattering is enhanced due to the magnetic dipole and magnetic quadrupole. The parameter tuning of the proposed device can tune this scattering. We have shown a dominating tunable magnetic quadrupolar scattering at some geometrical parameters. Moreover, graphene has a tunable chemical potential, allowing us to tune the resonance wavelength up to 30 µm. We have shown two tuning schemes to this range with the advantage of a double graphene structure. Along with the interplay of the multipole analysis of these plasmonic resonances, we have shown practical application to sensing. A chemical solvent sensor for detecting hazardous solvents like benzene and nitrobenzene has been proposed, considering the experimental dispersion of these compounds. The chemical solvent sensor has shown a maximum sensitivity of 1307.716 nm/RIU. We also have shown a potential application for high-sensitivity sensing where the refractive index changes only a fraction compared to the base parameter of the air environment, reporting a maximum sensitivity of 4830.95 nm/RIU.