Exciting surface plasmon polaritons in the Kretschmann configuration by light beam

TL;DR

This paper demonstrates that surface plasmon polaritons in the Kretschmann configuration are excited by narrow light beams composed of multiple plane waves, not by single plane waves at angles above total internal reflection.

Contribution

It reveals that surface plasmon polaritons are excited through interference effects of a beam's edges, challenging the common belief about excitation conditions.

Findings

Surface plasmon polaritons are excited by narrow beams, not single plane waves.

Excitation occurs at the beam's geometrical edges due to interference.

Plane waves incident at angles above total internal reflection do not excite SPPs.

Abstract

We consider exciting surface plasmon polaritons in the Kretschmann configuration. Contrary to common belief, we show that a plane wave incident at an angle greater than the angle of total internal reflection does not excite surface plasmon polaritons. These excitations do arise, however, if the incident light forms a narrow beam composed of an infinite number of plane waves. The surface plasmon polariton is formed at the geometrical edge of the beam as a result of interference of reflected plane waves.