Surface plasmon-polaritons in graphene, embedded into medium with gain and losses

TL;DR

This paper theoretically investigates how embedding graphene with gain and loss regions affects surface plasmon-polaritons, revealing new modes and tunable exceptional points influenced by doping and electrostatic gating.

Contribution

It introduces the concept of gain and loss in graphene plasmonics, showing the emergence of new modes and tunable exceptional points not present in conservative systems.

Findings

Additional plasmon-polariton modes due to gain and losses

Tunable exceptional points via graphene doping

Spectral singularities adjustable by electrostatic gating

Abstract

The paper deals with the theoretical consideration of surface plasmon-polaritons in the graphene monolayer, embedded into dielectric with spatially separated gain and losses. It is demonstrated, that presence of gain and losses in the system leads to the formation of additional mode of graphene surface plasmon-polaritons, which does not have its counterpart in the conservative system. When the gain and losses are mutually balanced, the position of exceptional point -- transition point between unbroken and broken $\mathcal{PT}$-symmetry -- can be effectively tuned by graphene's doping. In the case of unbalanced gain and losses the spectrum of surface plasmon-polaritons contains spectral singularity, whose frequency is also adjustable through the electrostatic gating of graphene.