We study THz pulses generated from plasmonic metal nanostructures under femtosecond illumination of near-IR light. We find two regimes of excitation, according to the order of the dependence of the THz fluence on the incident near-IR intensity: less then second order at low intensities, changing to approximately fourth order for higher intensities. These regimes are most likely associated with two THz generation mechanisms: optical rectification, and the ponderomotive acceleration of ejected electrons. These data provide evidence that both mechanisms can be at work in the same experiment.
|Journal||Physical review B: Condensed matter and materials physics|
|Publication status||Published - 2014|
Polyushkin, D. K., Marton, I., Racz, P., Dombi, P., Hendry, E., & Barnes, W. L. (2014). Mechanisms of THz generation from silver nanoparticle and nanohole arrays. Physical review B: Condensed matter and materials physics, 89(12), -. . https://doi.org/10.1103/PhysRevB.89.125426