Resonant excitation of surface modes at a single flat uniaxial–metal interface

A theoretical study about the propagation and resonant excitation of surface modes at the flat interface between a uniaxial crystal and a metal is performed. We show the existence of a class of surface modes that, under adequate conditions, and contrary to what happens for isotropic interfaces, can be coupled directly to incident radiation. We also show that the resonant excitation of these surface modes is correlated with a strong enhancement of the field on the surface and with a strong absorption of power by the metal. We study the influence of the orientation of the optic axis on these phenomena and show the existence of critical orientations for which all the incident power is absorbed by the metal.