This thesis discusses the power scaling of ultrashort pulses in enhancement cavities, utilized in particular for frequency conversion processes, such as Thomson scattering and high-harmonic generation. Using custom optics for ultrashort-pulse enhancement cavities, it demonstrates for the first time that at the envisaged power levels, the mitigation of thermal effects becomes indispensable even in cavities comprising solely reflective optics. It also studies cavities with large beams, albeit with low misalignment sensitivity, as a way to circumvent intensity-induced mirror damage. Average powers of several hundred kilowatts are demonstrated, which benefit hard x-ray sources based on Thomson scattering. Furthermore, pulses as short as 30 fs were obtained at more than 10 kW of average power and employed for high-harmonic generation with photon energies exceeding 100 eV at 250 MHz repetition rate, paving the way for frequency comb spectroscopy in this spectral region.
Nominated as an outstanding PhD thesis by the Max Planck Institute of Quantum Optics, Germany Achieves an order of magnitude improvement in the average power of ultrashort pulses Offers direct benefit efficient operation of hard X-ray sources Leads to compact alternatives to large-scale synchrotron facilities
Henning Carstens
High-power Enhancement Cavity Cavity-enhanced Thomson Scattering Thermal Mirror Deformation High-repetition Rate High-harmonic Generation XUV Frequency Comb