Surface plasmon polaritons in metal films on anisotropic and bianisotropic substrates

The existence of nonradiative surface plasmon polaritons (SPPs) is theoretically studied in an isotropic metal film surrounded by optically anisotropic half-infinite dielectrics. By using general properties of the impedance matrices of half-infinite dielectrics and metal films the maximum number of SPPs has been established at a given value of the tangential wave number. It has been proved that, if the dielectrics are nonbianisotropic and magneto-optically inactive but uniaxial or biaxial and oriented arbitrarily, then at most two SPPs can exist independently of the frequency dispersion of the dielectric permittivity and magnetic permeability. At most four SPPs emerge when both the dielectric media are bianisotropic and/or magneto-optically active but the maximum number of SPPs reduces to 3 provided that one of the dielectrics does not exhibit either bianisotropy or magneto-optical activity. A metal film inserted into an infinite bianisotropic and/or magneto-optically active medium can also guide at most three SPPs.