Second harmonic spectroscopy of ZnO, BiFeO₃ and LiNbO₃ nanocrystals

Abstract

We developed a wavelength-tunable second harmonic scattering experimental setup to investigate dispersion of the nonlinear optical response of three different nanocrystal suspensions (LiNbO3, ZnO and BiFeO3). Special attention was paid to reproducibility issues with the implementation of a detailed protocol that allows correcting for the setup spectral response. The absolute, orientation-averaged second order susceptibilities of the three nanomaterials were then assessed in the 700-1300 nm spectral range evidencing very specific optical signatures. The well-defined resonances observed for ZnO and BiFeO3 near their electronic transitions were found to be poorly described by the Miller's rule.