Electrostatic control over optically-pumped hot electrons in optical gap antennas

TL;DR

This paper demonstrates how a static electric field can modulate the nonlinear photoluminescence of an optical gap antenna by controlling surface charge density, enabling significant enhancement or reduction of emission.

Contribution

It introduces a method to electrically control hot electron emission in optical gap antennas, showing large modulation depths with low voltages.

Findings

Electric field modulates nonlinear photoluminescence yield.

Surface charge density influences electron temperature and emission.

Over 100% modulation depth achieved with a few volts.

Abstract

We investigate the influence of a static electric field on the incoherent nonlinear response of an unloaded electrically-contacted nanoscale optical gap antenna. Upon excitation by a tightly focused near-infrared femtosecond laser beam, a transient elevated temperature of the electronic distribution results in a broadband emission of nonlinear photoluminescence (N-PL). We demonstrate a modulation of the yield at which driving photons are frequency up-converted by means of an external control of the electronic surface charge density. We show that the electron temperature and consequently the N-PL intensity can be enhanced or reduced depending on the command polarity and the strength of the control static field. A modulation depth larger than 100\% is observed for activation voltages of a few volts.