Surface-assisted ultralocalization in nondiffracting beams

We present a family of localized radiation modes in multilayered periodic media, where in-phase superposition of p-polarized waves leads to radiative confinement around the beam axis. Excitation of surface plasmon polaritons yields an enhanced localization normally to the interfaces. On the other hand, the spectral filtering induced by the presence of bandgaps allows to achieve transverse superresolution on the interfaces. Subwavelength beamwidths along an infinitely long distance might potentially be obtained.