Tilting the pump pulse front has been proposed for efficient
phase-matched THz generation by optical rectification of
femtosecond laser pulses in LiNbO3 (Hebling et al., 2002). By
using amplified Ti:sapphire laser systems for pumping, this
technique has recently resulted in generation of near-single-
cycle THz pulses with energies on the 10-μJ scale (Yeh et al.,
2007, Stepanov et al., 2008). Such high-energy THz pulses have
opened up the field of sub-picosecond THz nonlinear optics and
spectroscopy (Gaal et al., 2006, Hebling et al., 2008a). The
method of tilted-pulse-front pumping (TPFP) was introduced as a
synchronization technique between the optical pump pulse and the
generated THz radiation. Synchronization was accomplished by
matching the group velocity of the optical pump pulse to the
phase velocity of the THz wave in a noncollinear propagation
geometry. Originally, TPFP was introduced for synchronization of
amplified and excitation pulses in so called traveling-wave
laser amplifiers (Bor et al., 1983).