Universal features of the optical properties of ultrathin plasmonic films

TL;DR

This paper theoretically investigates how the optical properties of ultrathin plasmonic films change with thickness, revealing tunable spatial dispersion and loss characteristics useful for designing advanced optical devices.

Contribution

It introduces a comprehensive theoretical model describing confinement effects and spatial dispersion in ultrathin plasmonic films as their thickness varies.

Findings

Plasma frequency shifts to the red as film thickness decreases.

Dissipative loss increases at the plasma frequency with thinner films.

Spatial dispersion becomes significant in ultrathin plasmonic films.

Abstract

We study theoretically confinement related effects in the optical response of thin plasmonic films of controlled variable thickness. While being constant for relatively thick films, the plasma frequency is shown to acquire spatial dispersion typical of two-dimensional materials such as graphene, gradually shifting to the red with the film thickness reduction. The dissipative loss, while decreasing at any fixed frequency, gradually goes up at the plasma frequency as it shifts to the red with the film thickness reduced. These features offer a controllable way to tune spatial dispersion and related optical properties of plasmonic films and metasurfaces on demand, by precisely controlling their thickness, material composition, and by choosing deposition substrates and coating layers appropriately.