Phase transition in PT symmetric active plasmonic systems

TL;DR

This paper investigates the phase transition in PT symmetric active plasmonic systems, deriving conditions for lossless surface plasmon polariton propagation and confirming findings through simulations.

Contribution

It provides an exact gain expression for loss compensation and identifies a phase transition point in PT symmetric plasmonic systems.

Findings

Derived an exact gain condition for lossless SPPs

Identified a critical gain value for phase transition

Validated results with COMSOL simulations

Abstract

Surface plasmon polaritons (SPPs) are coherent electromagnetic surface waves trapped on an insulator-conductor interface. The SPPs decay exponentially along the propagation due to conductor losses, restricting the SPPs propagation length to few microns. Gain materials can be used to counterbalance the aforementioned losses. We provide an exact expression for the gain, in terms of the optical properties of the interface, for which the losses are eliminated. In addition, we show that systems characterized by lossless SPP propagation are related to PT symmetric systems. Furthermore, we derive an analytical critical value of the gain describing a phase transition between lossless and prohibited SPPs propagation. The regime of the aforementioned propagation can be directed by the optical properties of the system under scrutiny. Finally, we perform COMSOL simulations verifying the theoretical findings.