Tunable Fano resonances in the decay rates of a pointlike emitter near a graphene-coated nanowire

TL;DR

This paper derives analytical expressions for decay rates of a dipole emitter near a graphene-coated nanowire, demonstrating tunable Fano resonances that can enhance or suppress light emission in the infrared range.

Contribution

It provides a theoretical framework for understanding and controlling Fano resonances in emitter decay rates near graphene-coated nanostructures, enabling tunable emission properties.

Findings

Fano resonances appear in the Purcell factor as a function of wavelength.

Fano line shape can be electrically tuned via chemical potential.

Resonant enhancement and suppression of emission achieved in the infrared.

Abstract

Based on the Lorenz-Mie theory, we derive analytical expressions of radiative and nonradiative transition rates for different orientations of a point dipole emitter in the vicinity of an infinitely long circular cylinder of arbitrary radius. Special attention is devoted to the spontaneous decay rate of a dipole emitter near a subwavelength-diameter nanowire coated with a graphene monolayer. We show that plasmonic Fano resonances associated with light scattering by graphene-coated nanowires appear in the Purcell factor as a function of transition wavelength. Furthermore, the Fano line shape of transition rates can be tailored and electrically tuned by varying the distance between emitter and cylinder and by modulating the graphene chemical potential, where the Fano asymmetry parameter is proportional to the square root of the chemical potential. This gate-voltage-tunable Fano resonance leads to a resonant enhancement and suppression of light emission in the far-infrared range of frequencies. This result could be explored in applications involving ultrahigh-contrast switching for spontaneous emission in specifically designed tunable plasmonic nanostructures.