Transverse spin with coupled plasmons

TL;DR

This paper theoretically investigates the transverse spin in coupled plasmon modes of a thin metal film, revealing how coupling influences spin magnitude and structure, with implications for spin enhancement in plasmonic devices.

Contribution

It provides a comprehensive analysis of the transverse spin in coupled plasmon modes, including effects of metal losses and analytical results in the lossless limit.

Findings

Short-range mode exhibits larger transverse spin due to higher decay.

Transverse spin depends directly on coupling strength and nature.

Analytical expressions derived for lossless case.

Abstract

We study theoretically the transverse spin associated with the eigenmodes of a thin metal film embedded in a dielectric. We show that the transverse spin has a direct dependence on the nature and strength of the coupling leading to two distinct branches for the long- and short- range modes. We show that the short-range mode exhibits larger extraordinary spin because of its more 'structured' nature due to higher decay in propagation. In contrast to some of the earlier studies, calculations are performed retaining the full lossy character of the metal. In the limit of vanishing losses we present analytical results for the extraordinary spin for both the coupled modes. The results can have direct implications for enhancing the elusive transverse spin exploiting the coupled plasmon structures.