Either with tremendous force or very quickly in a row - that's how you could describe the current state of laser technology. Physicists at the Max Born Institute (MBI) in Berlin want to combine both in close cooperation with the diode laser specialists of the Ferdinand Braun Institute (FBH). Their goal is lasers that have high single-pulse powers and can be fired at least a hundred times a second. For the development of such lasers, researchers received 3 million euros from the European Union (European Regional Development Fund - ERDF). The total budget of the project is 6 million.
High intensity lasers are a relatively recent product of physical research. They can emit single light pulses with unimaginable power - far more than the power of all the power plants in the world together. At the same time, the energy of the individual pulse is compressed into a period that is significantly shorter than one millionth of a millionth of a second. Because of their high single pulse power, such lasers are revolutionizing many areas of science, engineering and medicine. They serve, among other things, the generation of new states of matter, the ultraprecision machining of materials or the generation of particle or photon radiation with unprecedented properties. It is even expected that within the next year nuclear fusion can be demonstrated for the first time using high-intensity lasers - perhaps a step towards a relatively clean and virtually inexhaustible source of energy.
However, a technological gap exists in almost all of these lasers: the repetition rate of their light pulses is limited and is 10 times per second (10 hertz), often much lower. "Even if the single pulses are incredibly powerful, the overall performance or average power of conventional high-intensity lasers is hardly more than 10 watts. This is comparable to an energy-saving lamp, "says MBI Director Professor Wolfgang Sandner, in whose area the new project is located.
This gap is where the new MBI laser development comes in. For several years, the institute has been a world leader in the field of picosecond lasers with high pulse energy and repetition rate, ie high average power. These systems can be fired more than a hundred times a second thanks to innovative, highly efficient cooling of the laser material. "In order to further increase the mean power of these lasers, we want above all to increase the energy of the individual pulses, first to a few joules, later probably to much more," announces MBI project manager Dr. Ing. Ingo Will. Such lasers would then have an average power in the kilowatt range with pulse durations of picoseconds and very high single pulse energies, which is still not achieved by any laser.
Such laser power packages are urgently needed, for example, as the technological basis for the major European property ELI. The abbreviation stands for Extreme Light Infrastructure, which will become the world's most powerful basic research laser. Initial designs for the front-end of a 10 petawatt laser demonstrator for the ELI project have already been completed. The pump laser for this frontend is currently being built at the MBI and will soon be delivered to the Institut d'Optique in Palaiseau, France.
The basic concept of the new lasers is a completely diode-pumped solid-state laser. One of the most promising laser architectures, the so-called disk laser architecture, was taken over by the cooperation partners IfSW Stuttgart, DLR Stuttgart and TRUMPF Lasertechnik GmbH and further developed in recent years with funds from the Berlin technology grant PROFIT and the Leibniz SAW program. From the project partner FBH come new pump diodes for the disk laser. The now approved ERDF project is funded by the Senate Department for Education, Science and Research of the State of Berlin. As the first milestone in-house, the MBI researchers want to use the new laser to power a globally unique compact X-ray laser. With a wavelength of 13 nanometers and a repetition rate of 100 hertz, it is intended to generate coherent X-ray radiation in the laboratory, which is otherwise only possible with large free-electron lasers such as FLASH in Hamburg. In the long term, disk lasers will serve as the energy source for the next generation of high-intensity lasers. In addition, the MBI plans to build a high-performance attosecond source in collaboration with Prof. Marc Vrakking, the newly appointed director at the MBI.