Finite-thickness effects in plasmonic films with periodic cylindrical anisotropy

Using the earlier developed Lagrange formalism[1], the plasma frequency and the dielectric response function are derived for finite-thickness plasmonic films formed by periodic parallel arrays of metallic cylinders embedded in a host dielectric matrix[2]. 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 by the film material composition, the film thickness, the cylinder length, the cylinder-radius-to-film-thickness ratio, and by an appropriate choice of substrates and superstrates of the film. The theory developed is discussed in application to the finite-thickness periodically aligned carbon nanotube film system as a potential candidate for the new generation of flexible multifunctional metasurfaces[3], for which the importance of the nondispersive interband plasmon modes of individual nanotubes is stressed in the ultrathin film regime. -- [1]I.V.Bondarev & V.M.Shalaev, Opt. Mater. Expr. 7, 3731 (2017); [2]I.V.Bondarev, arXiv1810.07303; [3]A.L.Falk, et al, Phys. Rev. Lett. 118, 257401 (2017).