Stretcher and Amplifier design for the LPA Drive Lasers ANGUS and KALDERA

Laser-plasma accelerators (LPAs) are a promising technology to build compact andcost-efficient accelerators for a variety of applications. To realize this promise, thereliability and long-term stability of the accelerated electrons have to be improved.Much of this improvement relates to the stability of the drive laser. Apart fromimproving passive stability, increasing the repetition rate of the laser from a few Hzto >100 Hz, enables the use of active stabilizations, that can account for many lowerfrequency contributions from e.g. mechanical vibrations and air-fluctuations. Theoverarching goal of the thesis is to develop setups for the Ti:Sa CPA TW-class lasersystems ANGUS and KALDERA, that allow for a stable laser performance andacceleration of high-quality electrons.To improve the long-term stability of the ANGUS laser, a new, more stable front-end,based on optical-parametric chirped-pulse amplification (OPCPA) was built. Thisthesis reports on the design, alignment and characterization of the stretcher, that wasrequired to integrate the OPCPA front-end into the laser system. The design goalwas to achieve a stable and tunable stretcher and to minimize the angular chirp ofthe output beam by alignment with a three-color-laser. The characterization of thestretcher and its implementation into the laser system, which led to the compressionof pulses to 31 fs with sub-percent pulse duration stability will be presented.With KALDERA a >100Hz repetition rate LPA drive laser is currently being developedon DESY campus. To withstand the >100W average power in the final pulsecompressor, multi-layer dielectric (MLD) gratings need to be used. This thesis reportson the development, setup and characterization of a two-transmission grating, two-passOeffner stretcher, that matches such a MLD compressor. Using this stretcher, compressionto sub-30 fs pulse lengths at Ti:Sa wavelength in an out-of-plane compressorwith MLD gratings could be demonstrated for the first time. The characterization ofthe output pulses showed the viability of the stretcher and compressor concept for theKALDERA laser and other future high-average power, TW, fs laser systems.To efficiently seed the final amplifiers, a Booster amplifier is required for the KALDERAlaser. The designed three-pass Ti:Sa amplifier provides 0.5-1mJ output energy andsub-percent energy stability. The stretcher and the Booster amplifier successfully seedthe KALDERA multi-pass amplifiers to saturation, enabling sub-0.5% energy stabilityin the final amplifier stage.