All-Optical Generation of Surface Plasmons in Graphene

TL;DR

This paper demonstrates an all-optical method to excite surface plasmons in graphene using nonlinear wave mixing, enabling control over plasmon properties with potential applications in nanophotonics.

Contribution

It introduces a novel all-optical coupling scheme leveraging graphene's nonlinear response to excite surface plasmons without patterning.

Findings

Successful coupling of visible light to graphene plasmons.

Controlled excitation of plasmons with specific wavevector and direction.

Photon efficiency approaching 10^-5 in experiments.

Abstract

Here we present an all-optical plasmon coupling scheme, utilising the intrinsic nonlinear optical response of graphene. We demonstrate coupling of free-space, visible light pulses to the surface plasmons in a planar, un-patterned graphene sheet by using nonlinear wave mixing to match both the wavevector and energy of the surface wave. By carefully controlling the phase-matching conditions, we show that one can excite surface plasmons with a defined wavevector and direction across a large frequency range, with an estimated photon efficiency in our experiments approaching $10^{-5}$.