Surface polaritons—propagating electromagnetic modes at interfaces

Surface polaritons are interface electromagnetic modes whose propagation constants depend on the dielectric constants and magnetic permeabilities of the interfacing media. We discuss here (i) the nature of the modes which exist at single-interface and at slab (two-interface) configurations, (ii) the methods for coupling bulk polaritons and surface polaritons, and (iii) the use of surface polaritons as electromagnetic probes of surfaces and interfaces.