Terahertz Nano-Streaking: Resolving Nearfields and Plasmon Propagation

We present the principles and recent applications of THz streaking spectroscopy at metallic nanostructures. The combination of strong THz near-fields with nonlinear photoemission enables novel schemes of femtosecond time-resolved detection at the nanoscale. Near-field THz-waveforms are sampled via nonlinear photoemission. We discuss the electron dynamics in strong THz near-fields with implications for the shaping of ultrashort electron pulses in the temporal and spectral domains, and for THz-induced field emission. Particularly, we present a recent application of streaking spectroscopy to clock the propagation and plasmonic nano-focusing of surface plasmon-polaritons with sub-10 fs temporal resolution.