Third-generation femtosecond technology

Femtosecond pulse generation was pioneered four decades ago using mode-locked dye lasers, which dominated the field for the following 20 years. Dye lasers were then replaced with titanium-doped sapphire (Ti:Sa) lasers, which have had their own two-decade reign. Broadband optical parametric amplifiers (OPAs) appeared on the horizon more than 20 years ago but have been lacking powerful, cost-effective picosecond pump sources for a long time. Diode-pumped ytterbium-doped solid-state lasers are about to change this state of affairs profoundly. They are able to deliver 1 ps scale pulses at kilowatt-scale average power levels, which, in thin-disk lasers, may come in combination with terawatt-scale peak powers. Broadband OPAs pumped by these sources hold promise for surpassing the performance of current femtosecond systems so dramatically as to justify referring to them as the next generation. Third-generation femtosecond technology (3FST) offers the potential for femtosecond light tunable over several octaves, multi-terawatt few-cycle pulses, and synthesized multi-octave light transients. Unique tunability, temporal confinement, and waveform variety in combination with unprecedented average powers will extend nonlinear optics and laser spectroscopy to previously inaccessible wavelength domains, ranging from the far IR to the x-ray regime. Here we review the underlying concepts, technologies, and proof-of-principle experiments. A conceptual design study of a prototypical tunable and wideband source demonstrates the potential of 3FST for pushing the frontiers of femtosecond and attosecond science.