Transient perturbative nonlinear responses of plasmonic materials

Abstract

Recent investigations on optical nonlinearities of plasmonic materials suggest their responses may be even beyond the usual perturbative description. To better understand these surprisingly strong responses, we develop here a simple but general approach to describe the nonlinear optical response of plasmonic materials up to nth perturbation order. We apply the approach to understand spectral broadening occurring in resonant metasurfaces and investigate the enhancement of multiharmonic generation from multiply resonant metasurfaces, predicting an over 1×106-fold enhancement of higher harmonics.