Franz Kärtner is Professor of Physics at the University of Hamburg and he leads the Ultrafast Optics & X-rays group at DESY. His main area of research is the control of photons and electrons with ever increasing precision, currently in the attosecond range with the goal to advance ultrafast light and electron sources from the THz to the X-ray wavelength range. The sources can be of table-top size or large-scale X-FELs that enable new techniques to advance our understanding of the structure and function of matter. Key areas are: femtosecond to attosecond precision timing distribution systems; cryogenic lasers producing ultra-short high-energy (Joule) pulses at high-average-power (kW) and nano-plasmonic field-emitter arrays. These technologies are combined to construct multi-octave-wide high-energy lightwaves or coherent free-electron lasers employing optical undulators to produce attosecond soft and hard X-ray pulses.