Ultrafast Plasmonic Control of Second Harmonic Generation

TL;DR

This paper demonstrates ultrafast control of second harmonic generation in plasmonic metasurfaces using a novel interferometric technique, enabling active manipulation of nonlinear optical signals at the nanoscale.

Contribution

It introduces a serrated nanogap plasmonic structure for efficient SHG and a new method to characterize ultrafast plasmonic near-fields with 100 attosecond resolution.

Findings

Achieved efficient SHG in a serrated nanogap plasmonic geometry.

Demonstrated ultrafast control of nonlinear signals using a novel interferometric technique.

Enabled active manipulation of nonlinear optical responses at the nanoscale.

Abstract

Efficient frequency conversion techniques are crucial to the development of plasmonic metasurfaces for information processing and signal modulation. In principle, nanoscale electric-field confinement in nonlinear materials enables higher harmonic conversion efficiencies per unit volume than those attainable in bulk materials. Here we demonstrate efficient second-harmonic generation (SHG) in a serrated nanogap plasmonic geometry that generates steep electric field gradients on a dielectric metasurface. An ultrafast pump is used to control plasmon-induced electric fields in a thin-film material with inversion symmetry that, without plasmonic enhancement, does not exhibit an an even-order nonlinear optical response. The temporal evolution of the plasmonic near-field is characterized with ~100as resolution using a novel nonlinear interferometric technique. The ability to manipulate nonlinear signals in a metamaterial geometry as demonstrated here is indispensable both to understanding the ultrafast nonlinear response of nanoscale materials, and to producing active, optically reconfigurable plasmonic devices