Superluminal localized solutions to Maxwell equations propagating along a waveguide: the finite-energy case.

In a previous paper we have shown localized (nonevanescent) solutions to Maxwell equations to exist, which propagate without distortion with superluminal speed along normal-sized waveguides, and consist in trains of "X-shaped" beams. Those solutions possessed infinite energy. In this paper we show how to obtain, by contrast, finite-energy solutions, with the same localization and superluminality properties.