Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

Abstract

We show that second harmonic generation can be enhanced by Fano resonant\ncoupling of asymmetric plasmonic metal nanostructures. We develop a theoretical\nmodel examining the effects of electromagnetic interaction between two metal\nnanostructures on the second harmonic generation. We compare the second\nharmonic generation efficiency of a single plasmonic metal nanostructure with\nthat of two coupled ones. We show that second harmonic generation from a single\nmetal nanostructure can be enhanced about 30 times by attaching a second metal\nnanostructure with a 10 times higher quality factor than that of the first one.\nThe origin of this enhancement is Fano resonant coupling of the two metal\nnanostructures. We support our findings on Fano enhancement of second harmonic\ngeneration by an experimental study of a coupled plasmonic system composed of a\nsilver nanoparticle and a silver nanowire on glass surface in which the ratio\nof the quality factors are also estimated to be around 10 times.\n