Abstract-Clocking plasmon nanofocusing by THz near-field streaking

Applied Physics Letters

Lara Wimmer, Benjamin Schröder, Murat Sivis, Georg Herink, and Claus Ropers

http://aip.scitation.org/doi/abs/10.1063/1.4991860

Scanning electron microscopy images of the nanotip used in the experiment. (a) Micrograph of the nanotip including a sketch of the experiment. (b) Close-up of the grating structure that is optimized for incident light of 800 nm. (c) Close-up of the tip apex (radius of curvature: 20 nm).

We apply terahertz (THz) near-field streaking in a nanofocusing geometry to investigate plasmon polariton propagation on the shaft of a conical nanotip. By evaluating the delay between a streaking spectrogram for plasmon-induced photoemission with a measurement for direct apex excitation, we obtain an average plasmon group velocity, which is in agreement with numerical simulations. Combining plasmon-induced photoemission with THz near-field streaking facilitates extensive control over localized photoelectron sources for time-resolved imaging and diffraction.