New Ideas for X-Ray Lasers

„For the first time we are able to set up such a short-wave emitting laser”, says MBI-scientist Dr. Peter Viktor Nickles. The new X-ray laser at MBI will be pumped by a newly developed diode laser. Up to now, most laboratories world-wide use solid-state lasers to deliver to the X-ray lasers a necessary energy, a process called pumping. However, these conventional pumping lasers are not stable enough to ensure accurate measurements. “Particularly in sequence of measurements, when we average the signals, we get fuzzy results”, says Nickles. Diode-lasers are far more stable and thus more suitable for the pumping process. They lead to more exact results and also allow high repetition rates, i.e. fast repeating pulses.

“Our concept to develop an X-ray laser pumped by a diode laser is completely new”, says Nickles. At the beginning MBI aims at repetition rates up to 100 pulses per second (100 Hz). This is only possible with diode lasers. The new X-ray laser should be ready for use by the end of 2007. “This marks a milestone in the development of X-ray lasers”, says Nickles. The Investitionsbank Berlin supports the MBI project through a special subsidizing programme for the promotion of research, innovation and technology (the German abbreviation is ProFIT).

The neighbouring Ferdinand Braun Institute (FBH) is also involved in this research project. FBH provides the special diode-lasers. These light-sources are based on new designs of laminar structures (epitaxy) and lateral structuring. The highly brilliant and efficient laser-diodes emit at wavelengths about 935 nanometers and allow simple and reliable beam formation at low production costs.

One of the great advantages of such an X-ray laser is its comparatively small size. Furthermore, the diode-based pumping lasers require less energy than solid-state pumping lasers. A couple of standard-sized desks would be sufficient to build such an X-ray laser. Thus, an intense short-wave light-source can easily be moved – a feature that is especially interesting for industrial applications.

Nickles comments: “Their flexibility and easy transport make them an interesting source of short-wave pulses complementary to short-wave free electrons lasers (FEL) which work as individual large-scale facilities based on particle accelerators.”

“Table-top X-ray lasers were an important topic of the 10th International Conference on X-Ray Lasers (ICXRL) in Berlin-Adlershof”, says Nickles who, together with his colleagues, has organized the renowned meeting. „Some well-known parameters were improved by colleagues”, reports Nickles on other talks at the conference. One group documented that an X-ray laser was transferred from one laboratory to another and successfully assembled again. More than hundred active participants as well as numerous guests from altogether fourteen countries had come to Berlin.