Abstract

Metal nanoantennas have proven to be excellent devices for controlling light-matter interaction in spatial regions much smaller than the wavelength. Special interest exists on optical experiments exploiting the nonlinear emission generated by these nanostructures upon excitation with ultrashort laser pulses. This context is essential also for a better understanding of the nonlinear response of noble metals. So far, attention was turned mainly on the independent investigation of coherent processes like third-harmonic generation (THG) [1] and incoherent ones like multi-photon photoluminescence (MPPL) [2] in gold. Here, we show how these higher-order processes compete when a single gold nano-device is excited with ultrashort light pulses. The investigation of the relative efficiency of THG and MPPL allows us to gain insight into the origin of gold optical nonlinearities.

© 2015 IEEE