Improved nonlinear plasmonic slot waveguide: a full study

TL;DR

This paper introduces an improved nonlinear plasmonic slot waveguide design with buffer layers that reduce losses, enable new mode profiles, and allow controlled mode transitions, supported by a comprehensive phase diagram and stability analysis.

Contribution

It presents a novel waveguide structure with buffer layers that enhances performance and mode control, expanding the possibilities for nonlinear plasmonic waveguides.

Findings

Reduced propagation losses compared to simple NPSWs

New mode profiles and extended operational regimes

Demonstrated mode stability via FDTD simulations

Abstract

We present a full study of an improved nonlinear plasmonic slot waveguides (NPSWs) in which buffer linear dielectric layers are added between the Kerr type nonlinear dielectric core and the two semi-infinite metal regions. For TM polarized waves, the inclusion of these supplementary layers have two consequences. First, they reduced the overall losses. Secondly, they modify the types of solutions that propagate in the NPSWs adding new profiles enlarging the possibilities offered by these nonlinear waveguides. Our structure also provides longer propagation length due to the decrease of the losses compared to the simple nonlinear slot waveguide and exhibits, for well-chosen refractive index or thickness of the buffer layer, a spatial transition of its main modes that can be controlled by the power. We provide a full phase diagram of the TM wave operating regimes of these improved NPSWs. The stability of the main TM modes is then demonstrated numerically using the FDTD. We also demonstrate the existence of TE waves for both linear and nonlinear cases (for some configurations) in which the maximum intensity is located in the middle of the waveguide. This kind of structures could be fabricated and characterized experimentally due to the realistic parameters chosen to model them.