Tunable UV-Emitters through Graphene Plasmons

TL;DR

This paper introduces a method to create tunable UV light emitters by leveraging graphene plasmons and radiative cascade chains in multi-level emitters, enabling control over far-field UV emission through electrical doping.

Contribution

It proposes a novel approach combining graphene plasmonics and radiative cascades to achieve electrically tunable UV emission at energies above 10 eV.

Findings

Far-field UV emission can be enhanced by two orders of magnitude.

Tuning the Fermi energy sharply switches emission lines.

Distance control modulates emission strength significantly.

Abstract

Control over the spontaneous emission of light through tailored optical environments remains a fundamental paradigm in nanophotonics. The use of highly-confined plasmons in materials such as graphene provides a promising platform to enhance transition rates in the IR-THz by many orders of magnitude. However, such enhancements involve near-field plasmon modes or other kinds of near-field coupling like quenching, and it is challenging to use these highly confined modes to harness light in the far-field due to the difficulty of plasmonic outcoupling. Here, we propose that through the use of radiative cascade chains in multi-level emitters, IR plasmons can be used to enhance far field spectra in the visible and UV range, even at energies greater than 10 eV. Combining Purcell-enhancement engineering, graphene plasmonics, and radiative cascade can result in a new type of UV emitter whose properties can be tuned by electrically doping graphene. Varying the distance between the emitter and the graphene surface can change the strength of the far-field emission lines by two orders of magnitude. We also find that the dependence of the far-field emission on the Fermi energy is potentially extremely sharp at the onset of interband transitions, allowing the Fermi energy to effectively serve as a "switch" for turning on and off certain plasmonic and far-field emissions.