Nondiffracting Bessel plasmons

We report on the existence of nondiffracting Bessel surface plasmon polaritons (SPPs), advancing at either superluminal or subluminal phase velocities. These wave fields feature deep subwavelength FWHM, but are supported by high-order homogeneous SPPs of a metal/dielectric (MD) superlattice. The beam axis can be relocated to any MD interface, by interfering multiple converging SPPs with controlled phase matching. Dissipative effects in metals lead to a diffraction-free regime that is limited by the energy attenuation length. However, the ultra-localization of the diffracted wave field might still be maintained by more than one order of magnitude.

This research was funded by the Spanish Ministry of Science and Innovation under the project TEC2009-11635, and by the Qatar National Research Fund under the project NPRP 09-462-1-074. S.V. and M.R.B. wish to acknowledge the support for this work provided by Serbian Ministry of Education and Science through grant No. III 45016.