Our activity concerning primary light sources is mostly devoted to the development of optical parametric chirped pulse amplifiers (OPCPA). Currently four major OPCPA systems with unique parameters are under development or have been completed recently:

• A 100 kHz OPCPA producing 190 µJ, 7 fs, CEP-stable pulses at 800 nm has recently been completed and is serving as driver laser in high repetition rate attosecond experiments. Link
   

• Ongoing OPCPA developments include a 5 µm OPCPA system operating at 1 kHz, to be used as driver laser for MBI’s time-resolved X-ray diffraction research. This system is at an advanced stage of development and has already demonstrated 80 fs, 3.5 mJ pulses, which represents a new peak performance level at this wavelength. Link
   

• Other long wavelength OPCPA systems under development are motivated by MBI´s research utilizing HHG in the water window for soft X-ray transient absorption studies. This includes a 1.55 μm signal/3.1 μm idler dual-beam 100 kHz OPCPA system, which has already delivered an unprecedented average power of 43 W at the 1.55 µm signal wavelength, in 51 fs long, passively CEP-stabilized laser pulses, accompanied by 12.5 W, 73 fs, 3.1 µm idler pulses. Link
   

• Moreover, a 10 kHz, 2.1 µm OPCPA system is currently under development, which is expected to deliver 3 mJ, few-cycle laser pulses. Together with a planned 3 µm OPCPA system of similar technology HHG in the spectral region of the water window and beyond will be the basis of a new application laboratory.

In connection with the development of the 5 µm OPCPA, MBI has made significant progress in the development of 2-µm picosecond pump lasers based on Ho:YLF chirped pulse amplifiers (CPA) reaching more than 10 GW peak power. Using these systems, parametric generation in small bandgap nonlinear materials will be explored, avoiding the two-photon absorption problem, enabling access to idler wavelengths up to 8 µm, where non-oxide nonlinear materials with excellent thermo-mechanical properties are available.

Moreover, intensive research is devoted to power scaling of new types of solid-state laser and amplification systems in the near-IR wavelength range around 2 µm and beyond, with extension to longer wavelengths up to 20 µm by parametric frequency conversion. Here the performance of novel gain media, such as rare-earth and transition metal doped crystals and ceramics is investigated together with a large variety of new mode-locking solutions. In parallel, the properties of novel non-oxide nonlinear crystals are assessed for efficient frequency conversion into the mid-infrared. These efforts pave the way towards new high-power long-wavelength femtosecond light systems based on OPCPA since they cover all the three essential aspects: pump and seed sources as well as the nonlinear medium.