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Fattahi, Hanieh (2015): Third-generation femtosecond technology. Dissertation, LMU München: Faculty of Physics



Chirped pulse amplification in solid-state lasers is currently the method of choice for producing high-energy ultrashort pulses, having surpassed the performance of dye lasers over 20 years ago. The third generation of femtosecond technology based on short-pulse-pumped optical parametric chirped pulse amplification (OPCPA) holds promise for providing few-cycle pulses with terawatt-scale peak powers and kilowatt-scale-average powers simultaneously, heralding the next wave of attosecond and femtosecond science. OPCPA laser systems pumped by near-1-ps pulses support broadband and efficient amplification of few-cycle pulses due to their unrivaled gain per unit length. This is rooted in the high threshold for dielectric breakdown of the nonlinear crystals for even shorter pump pulse durations. Concomitantly, short pump pulses simplify dispersion management and improve the temporal contrast of the amplified signal. This thesis covers the main experimental and theoretical steps required to design and operate a high-power, high-energy, few-cycle OPCPA. This includes the generation of a broadband, high-contrast, carrier envelope phase (CEP)-stable seed, the practical use of a high-power thin-disk regenerative amplifier, its efficient use for pumping a multi-stage OPCPA chain and compression of the resulting pulses. A theoretical exploration of the concept and its extension to different modes of operation, including widely-tunable, high-power multi-cycle pulse trains, and ultrabroadband waveform synthesis is presented. Finally, a conceptual design of a field synthesizer with multi-terawatt, multi-octave light transients is discussed, which holds promise for extending the photon energy attainable via high harmonic generation to several kiloelectronvolts, nourishing the hope for attosecond spectroscopy at hard-x-ray wavelengths.