Nonlinear Plasmonics in 2-D materials

Surface plasmons are collective oscillations of electrons and light confined at a material interface.  Because of the hybrid coupling between light and matter, plasmons interact much more strongly than photons do.  Based on this simple idea, we would like to use plasmons as an intermediary system to make photons interact.  This idea is not new, however. It is well-known that plasmonic excitations can enhance optical nonlinearities. The problem is that in most materials plasmons decay too fast to be useful for quantum applications.  Thus, we are interested in finding material platforms that support long-lived plasmons.
To this end, our work on plasmon enhanced nonlinear interactions has thus far focused on two platforms: graphene and ultra-thin (~10 atomic layers) crystalline metal films.  In both cases, the nonlinear medium supports plasmons which are much longer lived and higher quality than those that can be achieved in bulk materials.  Roughly speaking, this occurs because in such thin media, the plasmonic field primarily “lives” outside of the plasmonic medium, so that losses from interactions with the material system are minimized.  So far, our work in this area has focused on using plasmonic resonances to enhance classical nonlinearities, but our goals are to reach the single photon regime, something which we have already analyzed in several theoretical proposals.