Scaling tilted-pulse-front based THz setups by control of the spatio-temporally coupled pump pulse parameters

We investigate both by experiments and simulations on how spatio-temporal coupling of pump pulse parameters in tilted-pulse-front based terahertz (THz) setups can be used to control the position of the "temporal focus", which is where minimum pump pulse duration is reached. This concept opens a pathway to pump tilted-pulse-front setups with arbitrarily stretched pump pulses which significantly simplifies pump pulse transport at high pulse energies. This concept is experimentally demonstrated by efficient operation of a tilted-pulse-front THz source with pump pulses stretched by a factor of x25 to 10 ps and extraction of a THz energy of 0.4 mJ while operating well-below damage threshold. Our findings are not only relevant for THz based particle acceleration and strong-field physics but any application that requires control over the temporal focus of beams with a tilted-pulse-front such as direct laser-based particle acceleration.