Phase Transition in \mathcal Symmetric Active Plasmonic Systems

• Published in: IEEE journal of selected topics in quantum electronics Vol. 22; no. 5; pp. 76 - 81
• Main Authors: Mattheakis, Marios, Oikonomou, Thomas, Molina, Mario I., Tsironis, George P.
• Format: Journal Article
• Language: English
• Published: IEEE 01.09.2016
• Subjects: active/gain materials; Conductors (devices); Dielectrics; Gain; Lossless; lossless propagation; Materials selection; mathcal {PT} symmetry; Metals; Optical properties; Optical surface waves; Permittivity; Phase transformations; Plasmons; Polaritons; Propagation losses; Resonant frequency; Surface plasmons polaritons; Symmetry; Surface plasmons polaritons; lossless propagation; active/gain materials; mathcal {PT} symmetry
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2015.2490018

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.