Finite-thickness effects in plasmonic films with periodic cylindrical anisotropy

TL;DR

This paper presents a theoretical analysis of how finite thickness influences the plasma frequency and dielectric response in plasmonic films with periodic cylindrical anisotropy, revealing tunable nonlocal effects.

Contribution

It introduces a theoretical framework to understand and control finite-thickness effects and spatial dispersion in plasmonic films with cylindrical anisotropy, including applications to carbon nanotube films.

Findings

Plasma frequency exhibits unidirectional square-root-of-momentum dispersion in thick films.

Ultrathin films show quasilinear momentum dispersion.

Dielectric response nonlocality can be tuned by material and geometric parameters.

Abstract

Finite-thickness effects are analyzed theoretically for the plasma frequency and associated dielectric response function of plasmonic films formed by periodically aligned, infinitely thin, identical metallic cylinders. The plasma frequency of the system is shown to have the unidirectional square-root-of-momentum and quasilinear momentum spatial dispersion for the thick and ultrathin films, respectively. This spatial dispersion and the unidirectional dielectric response nonlocality associated with it can be adjusted not only by the film material composition but also by varying the film thickness, the cylinder length, the cylinder-radius-to-film-thickness ratio, and by choosing the substrates and superstrates of the film appropriately. Application of the theory developed to the finite-thickness periodically aligned carbon nanotube films is discussed.