ELI ALPS and Class 5 Photonics tackle the next step in attosecond sources

The Extreme Light Infrastructure Attosecond Light Pulse Source (ELI ALPS) in Szeged, Hungary and Class 5 Photonics have signed a research and development contract for the new Mid-Infrared High-Energy (MIR-HE) laser and attosecond beamline (MIR-HE ATTO) at ELI ALPS.

ELI ALPS is a research facility providing cutting-edge laser systems and secondary sources for worldwide users. The focus of the institution is on so-called attosecond light pulses, an extreme form of laser light with two remarkable properties: These light pulses have a wavelength typically in the extreme ultraviolet region from 10 - 100 nm, thus allowing observations of nanometer scale objects. Further, the short light flashes have such extraordinarily short duration that even the motion of electrons can be captured (1 attosecond = 0.000000000000000001 seconds).

ELI Alps and Class 5 Photonics team during contract signature in Szeged, Hungary.

With the MIR-HE ATTO source, Class 5 Photonics and ELI want to take the technology one step further: Current sources are limited in the available power and the ultimately accessible wavelength. For the first time, attosecond pulses with a wavelength shorter than 1 nm will be generated. “This project is an outstanding opportunity for Class 5 Photonics and totally within the DNA of our team.” says Dr. Torsten Golz, who is leading the project at Class 5 Photonics.

In order to reach such remarkable light properties 1000 times per second (1 kHz) a new high-energy mid-infrared laser system is being developed by Class 5 Photonics. The MIR-HE laser is an optical parametric chirped-pulse amplifier (OPCPA), a method to generate ultrashort pulses at different wavelengths and the specialty of the Class 5 Photonics team for more than ten years. The MIR-HE laser system will additionally comprise the most advanced laser technologies, such as spectral phase-shapers, adaptive mirrors, and nonlinear spectral broadening. One of the key components is a high-power picosecond thin-disk laser provided by Trumpf Scientific Lasers in Munich, Germany, which delivers 200 mJ pulse energy at 1 kHz repetition rate. The final output specifications of the MIR-HE laser are 3 μm wavelength, 20 mJ pulse energy, 1 kHz pulse repetition rate and 25 fs pulse duration with stable carrier-envelope phase (CEP).

The intense mid-infrared pulses from the MIR-HE laser will be focused in a high-density gas target, specially developed by Class 5 Photonics. Here, the infrared laser pulses will be converted to soft X-ray pulses with photon energies exceeding 1 keV, corresponding to wavelengths below 1 nm. The physical process is called higher-harmonic generation (HHG). Class 5 Photonics has a team of experts who are experienced in highest power laser development and extreme ultraviolet to soft X-ray generation. Within the next two years, the team will develop not only the MIR-HE laser and the MIR-HE ATTO HHG source, but also the complete MIR-HE ATTO beamline, including the experimental end-station for cutting-edge attosecond spectroscopy techniques. First experiments are planned in 2023 in joint collaboration with ELI ALPS.