Enhanced Second Harmonic Generation From Coupled Asymmetric Plasmonic Metal Nanostructures

Abstract

We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce similar to 30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS.