Novel nonlinear chiroptical scattering effects

Recently, novel chiroptical harmonic scattering effects were reported, and the associated techniques have emerged as promising tools for characterizing the chirality of light scatterers, randomly dispersed in isotropic liquids. So far, the associated new physical effects have only been demonstrated in a handful of materials. For each material, only one size distribution has been studied. While third-harmonic chiroptical scattering, in the Rayleigh regime, has previously been demonstrated from Ag nanohelices, the data were only collected for right-handed scattering, with respect to the wavevector of incident light. Here, we present third-harmonic chiroptical scattering from Ag nanohelices with larger dimensions than those studied before. Moreover, we provide data in both right-handed and forward scattering. Our data are consistent with hyper-Rayleigh scattering and demonstrate that the recorded signal follows a cubic law with respect to the illumination laser power. Additionally, the obtained third-harmonic ellipticities clearly distinguish between left- and right-handed Ag nanohelices. The results reported here contribute to establish the applicability of chiroptical harmonic scattering to scatterers with various sizes, randomly dispersed in isotropic liquids.