Interference of surface plasmon polaritons from a "point" source

TL;DR

This paper demonstrates the generation and observation of interference patterns of surface plasmon polaritons from a highly coherent 100 nm point source on a metal surface, advancing plasmonic research capabilities.

Contribution

It introduces a novel near-field excitation method to create a coherent point SPP source with precise positioning, enabling detailed interference studies.

Findings

Observed clear interference patterns from the point source

Patterns agree well with numerical calculations

High coherence of the source enhances plasmonic investigations

Abstract

The interference patterns of the surface plasmon polaritons(SPPs) on the metal surface from a "point" source are observed. These interference patterns come from the forward SPPs and the reflected one from the obstacles, such as straightedge,corner, and ring groove structure. Innovation to the previous works, a "point" SPPs source with diameter of 100 nm is generated at the freely chosen positions on Au/air interface using near field excitation method. Such a "point" source provides good enough coherence to generate obvious interference phenomenon. The constructive and destructive interference patterns of the SPPs agree well with the numerical caculation. This "point" SPPs source may be useful in the investigation of plasmonics for its high coherence, deterministic position and minimum requirement for the initial light source.