Investigation of plasmonic whispering-gallery mode characteristics for graphene monolayer coated dielectric nanodisks

Abstract

In this Letter, we theoretically studied high-quality (Q) factor plasmonic whispering-gallery modes (WGMs) with ultrasmall mode volumes in graphene monolayer coated semiconductor nanodisks in the mid-infrared range. The influence of the chemical potential, the relaxation time of graphene, and the radius of the nanodisk on the cavity Q factor and the mode volume was numerically investigated. The numerical simulations showed that the plasmonic WGMs excited in this cavity had a deep subwavelength mode volume of 1.4×10(-5)(λ(0)/2n)(3), a cavity Q factor as high as 266 at a temperature lower than 250 K, and, consequently, a large Purcell factor of ∼1.2×10(7) when the chemical potential and relaxation time were assumed to be 0.9 eV and 1.4 ps, respectively. The results provide a possible application of plasmonic WGMs in the integration of nano-optoelectronic devices based on graphene.

Mode Coupling Properties of the Plasmonic Dimers Composed of Graphene Nanodisks

“…The surface conductivity of graphene σ g , composed of the interband electron transitions σ inter and the intraband electron-photon scattering σ intra , is given by the Kubo formula [17,[27][28][29],…”

“…Recently, graphene, which is composed of a single layer of carbon atoms arranged in a two-dimensional (2D) honeycomb lattice, has attracted great attention in the fields of electronics and photonics all over the world due to its excellent material properties [15][16][17]. More specifically, in the field of the plasmonics, graphene offers the advantages of high confinement capability, low damping loss and tunability of working frequency.…”

Investigation of the Band Structure of Graphene-Based Plasmonic Photonic Crystals

“…Therefore, the surface current density of graphene is defined as J = σ g E along the graphene sheet [42,43,44], where E is the electric field of the plasmon. The surface conductivity of graphene σ g , constituted by the interband electron transitions σ inter and the intraband electron-photon scattering σ intra , is obtained from the Kubo formula [45,46,47,48], ${\sigma }_g={\sigma }_{\mathrm{int}ra}+{\sigma }_{\mathrm{int}er}$ with ${\sigma }_{\mathrm{int}ra}=\frac{-i{e}^2{k}_{B}T}{\pi h^{2}false(\omega -i/\tau false)}\left[\frac{{\mu }_c}{k_{B}T}+2\ln \left(1+\exp false(-\frac{{\mu }_c}{k_{B}T}false)\right)\right]$ ${\sigma }_{\mathrm{int}er}=\frac{-i{e}^2}{2h}\ln \left[\frac{2\left|{\mu }_c\right|-hfalse(\omega -i/\tau false)}{2\left|{\mu }_c\right|+hfalse(\omega -i/\tau false)}\right]$ where μ c is the chemical potential, k B is the Boltzmann constant, T is the temperature, ω is the angular frequency of the plasmon, and τ is the electron momentum relaxation time.…”

Symmetry-Breaking Effect on the Electromagnetic Properties of Plasmonic Trimers Composed of Graphene Nanodisks

“…However, even the best conventional plasmonic materials, such as gold and silver, suffered huge ohmic losses in the frequency regime of interest. Also, once the geometry of PMs is determined, the electromagnetic (EM) properties are unable to tune, which becomes a bottleneck to further progress for metal-based PMs [16].…”