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O: Fachverband Oberflächenphysik

O 45: Poster Tuesday: Ultrafast Processes

O 45.5: Poster

Dienstag, 2. April 2019, 18:00–20:00, Poster D

High harmonic generation up to the keV regime and further applications of mid-infrared radiation — •Oscar Andres Naranjo Montoya, Manuel Bridger, Alexander Tarasevitch, and Uwe Bovensiepen — Universität Duisburg-Essen, Fakultät für Physik, 47057 Duisburg, Germany

Pump-probe experiments with optical excitation and absorption spectroscopy in the soft X-ray range on a femtosecond timescale are useful to analyze electronic and magnetic properties of complex material systems and their temporal evolution. Tabletop generation of soft x-rays pulses has become available using high harmonic generation driven by mid-infrared (MIR) femtosecond pulses in noble gases[1].

We developed a two-step Optical Parametric Chirped Pulse Amplifier that delivers sub 50 fs pulses at a wavelength of 3200 nm and energy >500 µJ as a pump for a tabletop soft x-ray source. That opens a door to perform a wide variety of soft x-ray experiments. Moreover, this MIR source also allows us to observe Floquet-Bloch states on the surfaces of topological insulators by femtosecond photoelectron spectroscopy[2]. We present the achieved spatial, spectral and temporal pulse characteristics of the MIR source as well as the estimate soft x-ray flux with some of the applications to be developed.

This work is funded by the DFG through SFB 1242, TP A05.

[1] T. Popmintchev et al., Science 336, 1287 (2012).

[2] F. Mahmood et al., Nature Phys. 12, 306 (2016)