High-Energy Single-Cycle THz Sources for Compact Particle Accelerators and Manipulators

Terahertz-driven (THz) accelerators and manipulators promise to yield short femtosecond electron bunches of high brightness with intrinsic synchronization to the driv-ing laser at a compact and economic footprint. However,development of practical devices requires THz sources thatreliably provide pulse energies in the sub-mJ to mJ regime,which in turn require state-of-the-art pump laser systemsand carefully designed optical transport lines. Here, we in-vestigate both by experiments and simulations on how spa-tio-temporal coupling of pump pulse parameters in tilted-pulse-front based terahertz setups can be used to controlthe position of the “temporal focus”, which is where mini-mum pump pulse duration is reached. This concept opensa pathway to pump tilted-pulse-front setups with arbitrarilystretched pulses which significantly simplifies transportlines for lasers with high peak intensity. This concept is ex-perimentally demonstrated by efficiently pumping a tilted-pulse-front THz source with pulses stretched to 10 ps andextraction of a THz energy of 0.4 mJ while operating well-below damage threshold. Our findings are not just relevantfor THz based particle acceleration and strong-field phys-ics but any application that requires control over the tem-poral focus of beams with a tilted-pulse-front such as othernovel laser-based particle accelerator schemes