08.06.2017 13:05

Publication in Scientific Reports

Super-efficient lasers thanks to plasma amplifier

With the help of a plasma amplifier, an international team of physicists, including researchers from Heinrich Heine University Düsseldorf (HHU), has succeeded in increasing a laser beam’s energy by 100 millionfold. Theoretical physicists from HHU were involved in the project, which was led by the University of Strathclyde in Scotland. They have now published their results in the journal Scientific Reports.

Caption: The experiments were carried out on the Vulcan high-power laser at the Rutherford Appleton Laboratory near Oxford. Seen in the picture is the experiment chamber with the Raman amplifier. (Photo: University of Strath-clyde)

High-performance lasers are required for various fields of application, such as the acceleration of elementary particles in new types of accelerator, inertial confinement fusion or cancer treatment. The primary lasers themselves do not achieve the necessary intensity, meaning that the primary laser beam needs optical amplification for such applications. This is mostly done nowadays with solid-state amplifiers, where the laser beam passes through an energetically charged amplifying medium and induces it to emit light itself by means of what is known as “stimulated emission”. This occurs synchronously with the irradiated laser light. However, solid-state amplifiers are very large and expensive and have a low damage threshold: There is a risk of damage to the appliances as a result of the high energy densities.

A promising alternative are what are known as Raman amplifiers. These are far more compact and cheaper than solid-state amplifiers. They are also very robust since the amplifying medium – gas plasma – cannot be destroyed. An international team of researchers from Scotland, Ireland, Portugal, South Korea, Czech Republic and Germany, led by the University of Strathclyde, has now and for the first time amplified up to 100 millijoules a short laser beam with an energy performance on picojoule scale. A record: The amplification factor is a hundred times higher than with high-power solid-state amplifiers. By way of illustration: With such a 100 millionfold amplification, the sound of rustling leaves would be as loud as a jumbo jet taking off.

The team of researchers at the Department of Theoretical Physics I at HHU led by Professor Alexander Pukhov delivered considerable input to the project. In the case of the high laser beam intensities targeted, what are known as “non-linear” phenomena occur that are not known from everyday practice. These include, amongst others, instabilities in the plasma that can lead to unwanted side effects. Dr. John Farmer from Professor Pukhov’s research group developed a computer simulation with the aid of which laser amplification processes can be analysed very quickly. Parameters can be adjusted in order to find the best operating settings for the laser amplifier.

Press release by the University of Strathclyde:


Original publication

G. Vieux, S. Cipiccia, D. W. Grant, N. Lemos, P. Grant, C. Ciocarlan, B. Ersfeld, M. S. Hur, P. Lepipas, G. G. Manahan, G. Raj, D. Reboredo Gil, A. Subiel, G. H. Welsh, S. M. Wiggins, S. R. Yoffe, J. P. Farmer, C. Aniculaesei, E. Brunetti, X. Yang, R. Heathcote, G. Nersisyan, C. L. S. Lewis, A. Pukhov, J. M. Dias & D. A. Jarozynski, An ultra-high gain and efficient amplifier based on Raman amplification in plasma, Scientific Reports, May 2017

Link: https://www.nature.com/articles/s41598-017-01783-4

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