Oblique launching of optical surface waves by a subwavelength slit

Abstract

The electromagnetic field on the metal surface launched by a subwavelength slit is analytically studied for the case when the fundamental mode inside the slit has a wave-vector component along the slit axis (conical mount). Both near-field and far-field regions are discussed, and the role of surface plasmon-polaritons and Norton waves is revealed. It is shown that the distance from the slit at which Norton waves are more intense than surface plasmons decreases with the parallel wave vector. Additionally, it is found that the s-polarization component, while present for any nonzero parallel wave vector, only weakly contributes to the Norton waves