Graphene-based plasmonic nanoantenna with trapezoidal structure in THz band

Abstract

Mainly manipulating emitted waves via plasmonic resonance is a fundamental characteristic of optical antennas. Plasmonic nanoantennas are used for terahertz (THz) radiation caused by optical interaction with surface resonance. The designed nanoantenna is such that the plasmonic resonance of the nanoantenna changes by controlling the graphene chemical potential (μc) from 0 eV to 0.2 eV. Although a dielectric layer separates the trapezoidal graphene sheets, an essential difference in the scattering parameters and the radiation pattern is observed since an external direct current bias changed the graphene surface impedance to about 860 Ω, which is the optimal value for reducing return loss in nano-systems. In other words, the plasmonic resonance frequencies can be tuned by the effect of a localised electrostatic field. Also, the trapezoidal graphene-based plasmonic nanoantenna has a high quality factor (Q-factor) from 2.35 to 5.71. Therefore, dynamic control, enhancing the input impedance and stable efficiency of graphene-based plasmonic nanoantennas, improves performance and matching at THz nano-systems for many applications of optoelectronic devices.