Impact of metallic mixing ratio on anisotropic coherent control of surface plasmon polaritons

Abstract

Metamaterials are engineered sub-wavelength structures designed to provide unusual electromagnetic properties, not found in natural materials. In particular, due to its direction-dependent nature, an anisotropic metamaterial (AMM) can provide precise control of surface plasmon polaritons (SPPs), enabling high field confinement and strong light-matter interactions at the nanoscale. In this work, we theoretically investigate the impacts of metallic content on the coherent control of SPPs at AMM/dielectric interfaces. The considered structure consists of alternating metal and dielectric layers, where the dielectric permittivity is described by a three-level $\Lambda -$type atomic system. From the perspective of coherent control, we analyze the dispersion relation, wavelength, and propagation length of SPPs under the influence of a probe detuning (${\Delta }_p$) and a control field ${\Omega }_c$. It is found that the increase in the metallic content, represented by the filling factor ($\alpha$), leads to significant enhancements in the dispersion and absorption spectrum of the SPPs, while reducing their wavelength and propagation length. These findings show that SPPs behavior can be controlled by engineering both the structural composition and the quantum coherence of the system, offering new possibilities for tunable plasmonic devices.