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Q: Fachverband Quantenoptik und Photonik
Q 64: Nano-Optics III
Q 64.2: Vortrag
Freitag, 4. März 2016, 11:15–11:30, f342
Few-cycle sub-10 femtosecond electron point source driven by nanofocused surface plasmon polaritons — •Melanie Müller1, Vasily Kravtsov2, Markus Raschke2, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2University of Colorado, Boulder, Colorado 80309, USA
We report the nonlocal excitation of sub-10 femtosecond electron pulses triggered by nanofocused surface plasmon polaritons (SPPs) from the apex of a gold nanotip. Few-cycle SPPs are launched 20 µm away from the apex by broadband grating coupling of 5 fs laser pulses at 800 nm. Nanolocalized photoemission from the apex is verified by the specific focusing conditions of the electron beam inside an electrostatic lens. We measure a pulse duration of 7-8 fs of the plasmonic near field, triggering multiphoton photoemission within a time window of 5 fs. We employ this conceptually new ultrafast electron source for plasmon-triggered femtosecond point-projection microscopy (fsPPM) at a tip-sample distance of 3 µm with a geometric magnification >30,000 and image the nanoscale field distribution along the surface of a doped semiconductor nanowire. The remote excitation scheme allows for a significant reduction of the tip-sample distance compared to conventional far-field illumination of the apex, promising few nanometer spatial and few femtosecond temporal resolution in fsPPM as well as the implementation of time-resolved low-energy electron holography.