Controlling plasmonic Bloch modes on periodic nanostructures

TL;DR

This paper demonstrates active control of plasmonic Bloch modes on nano-hole arrays using a spatial light modulator, revealing how to manipulate surface plasmon polaritons for enhanced sensing and microscopy applications.

Contribution

It introduces a method to actively control and observe dressed plasmonic modes on periodic nanostructures using programmable phase patterns.

Findings

SPP interference fringes observed with high contrast

Momentum of dressed plasmons depends on grating period

Potential to exceed traditional SPP momentum

Abstract

We study and actively control the coherent properties of Surface Plasmon Polaritons (SPPs) optically exited on a nano-hole array. Amplitude and phase of the optical excitation are externally controlled via a digital spatial light modulator (SLM) and SPP interference fringe patterns are observed with high contrast. Our interferometric observations revel SPPs dressed with the Bloch modes of the periodic nano-structure. The momentum associated with these Dressed Plasmons (DP) is highly dependent on the grating period and fully matches our theoretical predictions. We show that the momentum of DP waves can in principle exceed the SPP momentum. Actively controlling DP waves via programmable phase patterns offers the potential for high field confinement applicable in sensing, Surface Enhanced Raman Scattering and plasmonic structured illumination microscopy.