PUB - Publikationen an der Universität Bielefeld

The combination of femtosecond polarization pulse shaping and time-resolved photoemission electron microscopy (TR-PEEM) enables the ultrafast coherent control of optical near-fields at nanostructured surfaces. The optical excitation is confined at locations separated by sub-wavelength spatial distance as well as femtosecond temporal delay providing the possibility of ultrafast spatiotemporal spectroscopy on the nanoscale. 2D nanoscopy is a nonlinear spectroscopy technique based on coherent optical 2D spectroscopy. Collinear sequences of ultrashort laser pulses with variable relative delays and phases transfer the local electron distribution into excited electronic states which is finally leading to localized electron emission. The local photoemission yield is detected via TR-PEEM permitting the retrieval of local spectroscopic information via phase cycling and Fourier transformation of the pulse delays. Ultrafast coherent control and 2D nanoscopy is applied to investigate artificially nanostructured devices as well as corrugated silver surfaces, which are relevant for SERS, and localization of photonic modes in amorphous silicon thin-film solar cells.