Dispersion of the nonlinear susceptibility in gold nanoantennas

Summary form only given. Optical nanoantennas are excellent tools for accessing the nonlinear response of noble metals owing to the strong enhancement of light-matter interaction occurring in the near-field. For example, excitation of gold nanostructures with intense radiation triggers both coherent and incoherent phenomena such as third-harmonic generation (THG) [1] and multi-photon photoluminescence (MPPL), respectively [2, 3]. In this work, we study the interplay between these frequency conversion mechanisms in order to unveil the effective 2
⁽³⁾
nonlinear response of metals.