Oblique launching of optical surface waves by a subwavelength slit

TL;DR

This paper provides an analytical study of how a subwavelength slit on a metal surface launches electromagnetic surface waves, revealing the roles of surface plasmons and Norton waves in different regions and conditions.

Contribution

It introduces an analytical model for surface wave excitation by a slit in conical mount, highlighting the behavior of Norton waves and surface plasmons in near- and far-field regions.

Findings

Norton waves become more intense than surface plasmons at shorter distances with increasing parallel wavevector.

The s-polarization component weakly contributes to Norton waves.

The model helps guide experimental studies of surface wave phenomena.

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 wavevector 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 NW are more intense than surface plasmons decrease with parallel wavevector, which could help experimental studies on Norton waves. Additionally, it is found that the s-polarization component, while present for any non-zero parallel wavevector, only weakly contributes to the NWs.