03 March 2015 Graphene boosts Nonlinear Wave Mixing Efficiencies

Plasmon-Enhanced Nonlinear Wave Mixing in Graphene makes it to the cover of ACS Photonics. The recent study “Plasmon-Enhanced Nonlinear Wave Mixing in Nanostructured Graphene” carried out by the ICFO researchers Joel Cox and ICREA Prof Javier García de Abajo, from the Nanophotonics theory research group, has demonstrated that, through plasmon enhancement, graphene nano-islands can be used to generate nonlinear wave mixing at the nano-scale, with amazingly high efficiencies. The illustration of this research has had the honor of gracing the cover of the magazine’s current issue.

Plasmons in metallic nanostructures are used to enhance nonlinear optical effects since they are able to concentrate and amplify light down to extremely small scales. However, they are hardly tunable in metals after the structure is fabricated, therefore limiting the choice of frequency combinations.

In this study, the researchers demonstrate that graphene nano-islands can support plasmons at multiple frequencies when electrically doped, resulting in extraordinarily high wave-mixing susceptibilities when one or more of the input or output frequencies coincide with a plasmon resonance. Furthermore, they discovered that by varying the doping charge density of a graphene nano-island, these enhanced wave-mixing scenarios can occur over a wide spectral range in the visible and near-infrared.

These results demonstrate that nano-graphene structures can be used to develop tunable nonlinear optical nano-devices, which have diverse applications including optical microscopy, biological imaging, and signal conversion at the nano-scale.