Nonlocal and Nonlinear Surface Plasmon Polaritons and Optical Spatial Solitons induced by the Thermocapillary Effect

TL;DR

This paper investigates how ohmic losses in metal-dielectric systems induce thermal effects that nonlocally and nonlinearly modify surface plasmon polariton propagation, leading to the discovery of thermally induced optical solitons.

Contribution

It introduces a new thermally driven nonlinear and nonlocal model for SPPs and demonstrates the existence of novel optical spatial solitons supported by this mechanism.

Findings

Derivation of the nonlinear nonlocal Schrödinger equation for SPPs.

Analytical and numerical evidence of thermally induced spatial solitons.

Identification of a thermally self-induced nonlinear mechanism affecting SPP propagation.

Abstract

We study the propagation of surface plasmon polaritons (SPPs) on a metal surface which hosts a thin film of a liquid dielectric. The ohmic losses, that are inherently present due to the coupling of SPPs to conductors' electron plasma, induce temperature gradients and fluid deformation driven by the thermocapillary effect, which lead to a nonlinear and nonlocal change of the effective dielectric constant. The latter extends beyond the regions of highest optical intensity, and constitutes a novel thermally self-induced mechanism that affects the propagation of the SPPs. We derive the nonlinear and nonlocal Schrodinger equation (NNLSE) that describes propagation of low intensity SPP beams, and show analytically and numerically that it supports a novel optical spatial soliton excitation.