Towards nanoscale multiplexing with parity-time symmetric plasmonic coaxial waveguides

TL;DR

This paper explores a theoretical approach to nanoscale mode-division multiplexing using PT symmetric coaxial plasmonic waveguides, enabling increased data density in nanophotonic networks.

Contribution

It introduces a novel PT symmetric coaxial waveguide design that supports thresholdless mode splitting for enhanced multiplexing capabilities.

Findings

PT symmetry breaks mode degeneracy creating hybrid modes.

Mode evolution analyzed with Hamiltonian and perturbation theory.

Design enables thresholdless mode transitions for multiplexing.

Abstract

We theoretically investigate a nanoscale mode-division multiplexing scheme based on parity-time (PT) symmetric coaxial plasmonic waveguides. Coaxial waveguides support paired degenerate modes corresponding to distinct orbital angular momentum states. PT symmetric inclusions of gain and loss break the degeneracy of the paired modes and create new hybrid modes without orbital angular momentum. This process can be made thresholdless by matching the mode order with the number of gain and loss sections within the coaxial ring. Using both a Hamiltonian formulation and degenerate perturbation theory, we show how the wavevectors and fields evolve with increased loss/gain and derive sufficient conditions for thresholdless transitions. As a multiplexing filter, this PT symmetric coaxial waveguide could help double density rates in on-chip nanophotonic networks.