Light-induced symmetry breaking for enhancing second-harmonic generation from an ultrathin plasmonic nanocavity.

ABSTRACT: Efficient frequency up-conversion of coherent light at the nanoscale is highly demanded for a variety of modern photonic applications, but it remains challenging in nanophotonics. Surface second-order nonlinearity of noble metals can be significantly boosted up by plasmon-induced field enhancement, however the related far-field second-harmonic generation (SHG) may also be quenched in highly symmetric plasmonic nanostructures despite huge near-field amplification. Here, we demonstrate that the SHG from a single gold nanosphere is significantly enhanced when tightly coupled to a metal film, even in the absence of a plasmon resonance at the SH frequency. The light-induced electromagnetic asymmetry in the nanogap junction efficiently suppresses the cancelling of locally generated SHG fields an

SUBMITTER: Li GC 

PROVIDER: S-EPMC8282679 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature