Enhanced nonlinear optical response of single metal-dielectric nanocavities resonating in the near-infrared

TL;DR

This paper demonstrates that multilayer metal-dielectric nanocavities can significantly enhance nonlinear optical responses, especially second-harmonic generation, by engineering absorption and symmetry breaking, surpassing traditional gold nanostructures.

Contribution

The study introduces a method to boost nonlinear optical effects in nanocavities by combining plasmonic and dielectric materials, achieving higher efficiency than existing gold nanostructures.

Findings

Achieved an order of magnitude increase in second-harmonic generation efficiency.

Estimated second-order nonlinear susceptibility of about 1 pm/V.

Enhanced nonlinear response compared to conventional gold nanostructures.

Abstract

Harmonic generation mechanisms are of great interest in nanoscience and nanotechnology, since they allow generating visible light by using near-infrared radiation, which is particularly suitable for its endless applications in bio-nanophotonics and opto-electronics. In this context, multilayer metal-dielectric nanocavities are widely used for light confinement and waveguiding at the nanoscale. They exhibit intense and localized resonances that can be conveniently tuned in the near-infrared and are therefore ideal for enhancing nonlinear effects in this spectral range. In this work, we experimentally investigate the nonlinear optical response of multilayer metal-dielectric nanocavities. By engineering their absorption efficiency and exploiting their intrinsic interface-induced symmetry breaking, we achieve one order of magnitude higher second-harmonic generation efficiency compared to gold nanostructures featuring the same geometry and resonant behavior. In particular, while the third order nonlinear susceptibility is comparable with that of bulk Au, we estimate a second order nonlinear susceptibility of the order of 1 pm/V, which is comparable with that of typical nonlinear crystals. We envision that our system, which combines the advantages of both plasmonic and dielectric materials, might enable the realization of composite and multi-functional nano-systems for an efficient manipulation of nonlinear optical processes at the nanoscale.