  We present a study on THz generation in lithium niobate pumped by a powerful
and versatile Yb:CaF2 laser. The unique laser system delivers transform-limited
pulses of variable duration (0.38-0.65 ps) with pulse energy of up to 15 mJ at
a center wavelength of 1030 nm. From theoretical investigations it is expected
that those laser parameters are ideally suited for efficient THz generation.
Here we present experimental results on both the conversion efficiency and the
THz spectral shape for variable pump pulse durations and for different crystal
temperatures down to 25 K. We experimentally verify the optimum pump parameters
for most efficient and broadband THz generation.
