Mie-enhanced photothermal/thermo-optical nonlinearity and applications on all-optical switch and super-resolution imaging [Invited]

Nonlinear optical interactions are of fundamental significance for advanced photonic applications, but usually the nonlinearity magnitude is insufficient. Here we review recent progresses to boost the optical nonlinearity of metal or semiconductor nanostructures via the combination of Mie resonance and coupled photothermal/thermo-optical effects. In plasmonic and silicon nanoparticles, the effective photothermal nonlinear index n 2 is enhanced by 10 3 and 10 5 times over that of bulk, respectively. The large nonlinearities enable applications of not only all-optical switch, but also super-resolution imaging based on suppression of scattering, saturation (sub-linearity) and reverse saturation (super-linearity).