Fano-control of down-conversion in a nonlinear crystal via plasmonic-quantum emitter hybrid structures

Control of the nonlinear response of nanostructures via path interference effects, i.e., Fano resonances, has been studied extensively. In such studies, a frequency conversion process takes place near a hot spot. Here, we study the case where the frequency conversion process takes place along the body of a nonlinear crystal .Metal nanoparticle- quantum emitter dimers control the down-conversion process, taking place throughout the crystal body, via introducing interfering conversion paths.Dimers behave as interaction centers.We showthat two orders of magnitude enhancement is possible, on top of the enhancement due to localization effects. That is, this factor multiplies the enhancement taking place due to the field localization.