| Popis: |
The objective of this work was the development of a laser module to improve the temporal contrast of high-intensity laser systems and its implementation at the high-power laser PHELIX at the GSI Helmholtzzentrum für Schwerionenforschung GmbH in Darmstadt. By improving the temporal contrast, experiments with laser-plasma interaction under extreme peak intensities should be made possible without disturbing or destroying the target before the arrival of the main pulse. In the frame of this work, I have therefore developed an ultrafast optical parametric amplifier (uOPA), which enables high-temporal-contrast amplification of short laser pulses up to the millijoule range and can thus replace subsequent contrast-degrading amplifier systems. In addition to reducing amplified spontaneous emission, the occurrence of pre-pulses can also be prevented. I have additionally developed a dedicated pump module for this amplifier, which can be used in a wide spectral range around the central wavelength of 1 μm and thereby can be implemented on various laser systems as a pump laser for uOPA systems. Thus, in addition to the high-contrast amplifier for the Nd:glass laser system PHELIX, I have built a second uOPA module for use in the diode-pumped Yb:CaF2 laser system PENELOPE. I implemented the module on the high-power PHELIX laser as part of this work, which successfully replaced an amplifier, which generated intense pre-pulses, in the amplification chain. This allowed me to lower the pre-pulse contrast at PHELIX by nearly three orders of magnitude to a contrast level of 6.2·10⁻¹¹, keeping the pre-pulse intensity, even for the highest possible intensity at PHELIX, below 100 GW/cm². |
