All optical Amplification in Metallic Subwavelength Linear Waveguides

TL;DR

This paper presents a linear optical amplification mechanism using coupled metallic subwavelength waveguides, where specific eigenmode superpositions lead to divergence in amplification rate at low signal levels.

Contribution

It introduces a novel all-optical amplification scheme based on eigenmode superpositions in metallic waveguides, with analytical and numerical validation.

Findings

Amplification rate diverges for small signals.

Stationary states are formed by superpositions of eigenmodes.

The mechanism is fully linear and relies on waveguide properties.

Abstract

Proposed all optical amplification scenario is based on the properties of light propagation in two coupled subwavelength metallic slab waveguides where for particular choice of waveguide parameters two propagating (symmetric) and non-propagating (antisymmetric) eigenmodes coexist. For such a setup incident beams realize boundary conditions for forming a stationary state as a superposition of mentioned eigenmodes. It is shown both analytically and numerically that amplification rate in this completely linear mechanism diverges for small signal values.