Conditions for achieving invisibility of hyperbolic multilayered nanotubes

• We investigated the scattering efficiency, with emphasis in the invisibility regime, of multilayered metal-dielectric nanotubes with configurations of a different ending layer.
• When the nonconducting layer remains in contact with the core of the hollow cylinder, the characteristic invisibility of the hyperbolic nanotube is cleared away.
• In this case there is an additional boosting of plasmonic-Bloch resonances markedly observed on the wave fields localized at the rear part of the multilayered nanocylinder.
• Furthermore, the effective medium theory enabling a simplified model for the optical characterization of the nanoparticle will lead to fallacious estimations.

Highly anisotropic plasmonic nanotubes exhibit a dramatic drop of the scattering cross section in the transition regime from hyperbolic to elliptic dispersion. The characterization of a realistic multilayered metamaterial is typically carried out by means of an effective medium approach providing average components of the permittivity tensor and wave fields. Here, the edge effects of the metal-dielectric stratified nanotube for different combinations were thoroughly analyzed. We show how the boundary layers, which in principle remain fully irrelevant in the estimation of the effective permittivity of the nanotube, however play a critical role in the resonant scattering spectra and the near field patterns. A remarkable enhancement of the scattered wave field is unexpectedly experienced at the frequencies of interest when a dielectric layer is chosen to be in contact with the cavity core.