All-optical directional switching of non-thermal photocurrents in plasmonic nanocircuits

TL;DR

This paper demonstrates the all-optical generation and directional control of non-thermal photocurrents in plasmonic nanocircuits, enabling ultrafast, reconfigurable on-chip optical control of electrical currents at the nanoscale.

Contribution

It introduces a method to control and detect non-thermal photocurrents in plasmonic circuits using light polarization and thermal gradients, advancing all-optical nanocircuit technology.

Findings

Directional control of photocurrents achieved via polarization tuning.

Separation of ultrafast drift currents from photothermal effects.

Remote detection of nanoscale photocurrents using thermal gradients.

Abstract

Controlling the flow of electricity in metallic circuits with light is a key goal for future optoelectronics. In this work, we demonstrate all-optical generation and directional control of non-thermal drift photocurrents in a plasmonic gold wire. We attribute this phenomenon to the Inverse Faraday Effect and show that the current's direction can be precisely reversed at a subwavelength scale by tailoring the incident light's polarization or laser beam position. A bespoke polarization modulation technique is employed to unambiguously separate ultrafast drift currents from the ubiquitous photothermal background. We further reveal a collaborative mechanism where macroscopic thermal gradients, acting as a driving force, are used to extract and remotely detect the locally-generated nanoscale photocurrents. This robust control and detection scheme paves the way for reconfigurable, all-optical nanocircuitry capable of ultrafast on-chip processing.