Dynamics, Efficiency, and Energy Distribution of Nonlinear Plasmon-Assisted Generation of Hot Carriers

We employ nonlinear autocorrelation measurements to investigate plasmon-assisted hot carrier dynamics occurring in optical gold antennas. A nonlinear formation of hot carriers is produced by the excitation of surface plasmons, providing thus a unique lever to optimize the energy distribution and generation efficiency of the photoexcited charges. The temporal response of the carriers' relaxation is controlled within a range extending from 500 fs to 2.5 ps. By conducting a quantitative analysis of the dynamics, we determine the nonlinear absorption cross-section of individual optical antennas. This work sheds new insights on the understanding of plasmon-induced hot carrier generation, especially in view of applications where the time response plays a preponderant role.