Ultrashort laser pulses enable high peak intensities to be achieved. These enable a series of fundamental investigations. A particularly interesting phenomenon occurs when the pulses are focused into a gas. Here, coherent radiation in the extreme ultraviolet range is generated.
In order to make fiber lasers usable for the generation of higher harmonics, hybrid concepts such as fiber laser-pumped parametric amplifiers or non-linear compression are used.
EUV radiation is used in time-resolved spectroscopy, for example.
To date, applicability in practice has been limited, as the laser systems use are limited in their pulse frequency and the process is inherently inefficient.
S. Hädrich, M. Krebs, J. Rothhardt, H. Carstens, S. Demmler, J. Limpert, and A. Tünnermann, »Generation of µW level plateau harmonics at high repetition rate«, Opt. Express 19, 19374-19383 (2011)
S. Demmler, J. Rothhardt, S. Hädrich, M. Krebs, A. Hage, J. Limpert, and A. Tünnermann, "Generation of high-photon flux-coherent soft x-ray radiation with few-cycle pulses," Opt. Lett. 38, 5051–5054 (2013)
S. Hädrich, A. Klenke, J. Rothhardt, M. Krebs, A. Hoffmann, O. Pronin, V. Pervak, J. Limpert, and A. Tünnermann, "High photon flux table-top coherent extreme ultraviolet source," Nat Phot. 8, 779–783 (2014)