Handy XUV Laser Robert Klas
Robert Klas at the laboratory. [Foto: Jan-Peter Kasper/FSU]

What happens inside atoms and molecules when they enter into a chemical bond? How does it looks, when light interact with optical nanomaterials? If researchers want to observe chemical reactions in real time or observe the movement of charge carriers, they are now using intense Extreme Ultraviolet (XUV) Radiation. But it does not come from an ordinary gas discharge lamp. "For such applications, coherent, extremely short pulsed XUV light is needed," emphasizes Prof. Dr. Jens Limpert. Such XUV pulses are usually generated in giant particle accelerators, such as the XFEL in Hamburg, whose 3.4 kilometer long underground plant has just been put into operation or in ring accelerators, so-called synchrotrons, with several hundred meters in diameter.
However, access to these powerful large-scale plants is limited, and not all scientific questions can be adequately investigated, which motivates the development of comparatively "handy" laser systems. In the current issue of the magazine "Optica", the physicists are presenting an experimental setup that allows ultrasound, intensive XUV pulses to be produced in practically every optics laboratory (DOI: 10.1364 / OPTICA.3.001167).

New imaging techniques for nanostructures

This publication shows how XUV pulses can be generated with significantly higher efficiency than was previously possible with systems of this magnitude. For this purpose laser pulses are focused in a double-breaking crystal, whereby the frequency of the originally infrared light is doubled. Laser pulses in the green wavelength range are the result. These are again refocused in a second step of the so-called cascaded frequency conversion, which results in even higher-frequency pulses in the XUV.

This way spectrally narrow-band and coherent XUV pulses emerge with a power in the milliwatt range. Their wavelength is only 57 nanometers. "Usual systems are only one hundredth of this power, while our fiber laser-based systems typically provide approximately 100 μW of average power - this new method is now even better," emphasizes Robert Klas, who has been realized the new source together with his colleagues in the laboratory. Thanks to this technique, the XUV sources can now also be used for practical applications, which are pursued in the Helmholtz Junior Research group, led by Dr. Jan Rothhardt - for example for new imaging methods to make three-dimensional structures visible with a resolution of a few 10 nanometers and so allow complete new insights into the world of nano.

Original Publication:

R. Klas et al. Table-top milliwatt-class extreme ultraviolet high harmonic light source, Optica 3, 1167-1170 (2016), DOI: 10.1364/OPTICA.3.001167


Prof. Dr. Jens Limpert
Tel.: 03641 / 947643, 03641 / 947811

Dr. Jan Rothhardt
Tel.: 03641 / 947818

german text here >>>

News from: 02.11.2016 09:34
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