Spaser and optical amplification conditions in graphene-coated active wires

Abstract

This work analyzes the optical properties of a localized surface plasmon (LSP) spaser made of a dielectric active wire coated with a graphene monolayer. Our theoretical results, obtained by using rigorous electromagnetic methods, illustrate the non-radiative transfer between the active medium and the LSPs of graphene. In particular, we focus on the lasing conditions and the tunability of the LSP spaser in two cases: when the wire is made of an infrared/terahertz transparent dielectric material and when it is made of a metal-like material. We analyze the results by comparing them with analytical expressions obtained by using the quasistatic approximation. We show that the studied systems present a high tunability of the spaser resonances with the geometrical parameters as well as with the chemical potential of graphene.

Terahertz lasing conditions of radiative and nonradiative propagating plasmon modes in graphene-coated cylinders

“…Reciprocally, they can be coupled to incident radiation without using any additional device, which is why normally incident plane waves were used as the excitation mechanism in Ref. [28]. On the other hand, the propagating modes studied in this paper exhibit radiative or nonradiative behavior depending on the value of k z .…”

“…Terahertz graphene-based spasers with cylindrical geometries, the kind of structure considered in this paper, were studied in [27] and [28]. Wheras in [27] the inner active medium consists of an axially-located single quantum wire and the analysis is limited to the electrostatic regime exclusively, here we consider that the active medium occupies the entire interior and we use a fully retarded rigorous electromagnetic analysis.…”

“…Wheras in [27] the inner active medium consists of an axially-located single quantum wire and the analysis is limited to the electrostatic regime exclusively, here we consider that the active medium occupies the entire interior and we use a fully retarded rigorous electromagnetic analysis. Regarding [28], the analyisis is limited to the particular case of localized surface plasmon modes, that is, standing surface waves along the azimuthal direction, with no propagation along the cylinder axis (k z = 0, Fig. 1) and with purely TE polarization (electric field perpendicular to the cylinder axis).…”

“…By contrast, in this paper we study spasers emitting propagating surface plasmon modes (k z = 0) which are not purely TE, but a combination of both TE and TM (magnetic field perpendicular to the cylinder axis) polarizations. The localized surface plasmons considered in [28] are radiative, in the sense that they emit radiation towards the exterior medium. Reciprocally, they can be coupled to incident radiation without using any additional device, which is why normally incident plane waves were used as the excitation mechanism in Ref.…”

Terahertz-range plasmon and whispering gallery mode resonances in the plane wave scattering from thin microsize dielectric disk with graphene covers

“…The resonances on the graphene plasmon modes are actively studied today and have already found applications in the design of novel biosensors [5][6][7] and antennas [8] in the mid-infrared and THz ranges. The use of graphene, instead of the noble metals, in the design of plasmonic nanolasers is also actively discussed [9].…”