Towards plasmonic-enhanced optical nonlinearities in graphene metal-heterostructures

The ability to concentrate light into nanometric volumes enables access to an ultrastrong light-matter coupling regime. Graphene-based platforms are extremely appealing for achieving this goal. Indeed, this unique 2D material possesses a strong third-order nonlinear response, which, thanks to the intense near-fields associated with the excitation of surface plasmons, can be made substantial even at the single-photon level [1] , [2] .