Shaping, imaging and controlling plasmonic interference fields at buried interfaces

TL;DR

This study demonstrates the real-time, nanometer-scale imaging and control of plasmonic interference fields at buried interfaces using photon-induced near-field electron microscopy, enabling advances in plasmonic device engineering.

Contribution

It introduces a method to excite, shape, and film plasmonic fields at buried interfaces with femtosecond and nanometer resolution, combining nanostructured design and PINEM imaging.

Findings

Plasmons propagate at approximately 0.3c, matching theoretical predictions.

Light polarization and nanocavity design can shape transient plasmonic gratings.

PINEM enables direct visualization of ultrafast plasmon dynamics.

Abstract

Filming and controlling plasmons at buried interfaces with nanometer (nm) and femtosecond (fs) resolution has yet to be achieved and is critical for next generation plasmonic/electronic devices. In this work, we use light to excite and shape a plasmonic interference pattern at a buried metal-dielectric interface in a nanostructured thin film. Plasmons are launched from a photoexcited array of nanocavities and their propagation is filmed via photon-induced near-field electron microscopy (PINEM). The resulting movie directly captures the plasmon dynamics, allowing quantification of their group velocity at approximately 0.3c, consistent with our theoretical predictions. Furthermore, we show that the light polarization and nanocavity design can be tailored to shape transient plasmonic gratings at the nanoscale. These results, demonstrating dynamical imaging with PINEM, pave the way for the fs/nm visualization and control of plasmonic fields in advanced heterostructures based on novel 2D materials such as graphene, MoS$_2$, and ultrathin metal films.