FLASH has been a user facility since 2005, delivering radiation in the wavelength range between 4.1 and 45 nm using the SASE principle. So far the user requests for beam time by far exceeds the time available. In order to increase user beam time and improve the radiation properties delivered to users, a mayor extension of the user facility called FLASH II has been proposed by DESY in collaboration with the HZB, which is a seeded FEL over the parameter range of FLASH. After several years of design, the project now enters its construction phase, which will last approximately 2 years. In the mean time, tests are performed in order to prepare for a multi-undulator operation of the facility. In addition, complete start-to-end simulations will complete the simulations which have been performed so far.

We present a new dual-gas multi-jet HHG source which can be perfectly controlled via phasematching of the long and short trajectory contributions and is applicable for high average power driver laser systems.

Ultra-fast laser sources have revolutionized many fields in science. As technology improves, new applications can be made accessible. The OPCPA technique has shown potential to be the key technology for future amplifier systems, but hasn’t achieved a breakthrough such as Ti:Sapphire laser technology, mostly due to the complex pump amplifier design. We present an operationally stable OPCPA system that might turn the tide for OPCPA technology. This first prototype system will be used in the accelerator environment at the FLASH free electron laser at DESY in Hamburg. The envisioned key parameters for this amplifier are >1 mJ pulse energy with a repetition rate of 100 kHz and a pulse duration of <7 fs.

Improved performance of Free Electron Laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in many fields of science. A promising scheme is direct seeding with High-Harmonic Generation (HHG) in a noble gas target. A Free-Electron-Laser seeded by an external XUV-source is planned for FLASH II at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within single harmonics.This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, sub-10 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new OPCPA system is under development in order to meet these requirements, and very promising results has been achieved. In parallel to this development, a new High-Harmonic Generation concept is necessary to sustain the high average power of the driving laser system and for the need of high conversion efficiencies. Highest conversion efficiency in High Harmonic Generation has been shown using gas-filled capillary targets, up to now. For our application, only a free-jet target is applicable for high harmonic generation at high repetition rate, to overcome damage threshold limitations of HHG target optics. A new multi-jet target is under development and first tests show a good performance of this nozzle configuration.