Influence of the dielectric substrate on the field emitted by a subwavelength slit in a metal film

The field emitted by a localized source in the metal surface bounding to a half-media with arbitrary dielectric permittivity is studied. The far field at the surface is composed of both the surface plasmon polariton and the algebraically decaying Norton wave contributions. The crossover distance at which the Norton wave overtakes the surface plasmon, depends upon the refractive index of the bounding media. Substrates with high dielectric permittivity bring the crossover substantially closer to the source. [GRAPHICS] The field emitted by a subwavelength slit. Far away from the source the field presents contributions from both the surface plasmon and the Norton wave. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim