Temporal and Spectral Shaping of Broadband THz Pulses in a Photoexcited   Semiconductor
  Transmission through photoexcited semiconductors is used to temporally and spectrally shape a Terahertz pulse. By adjusting the optical pump-THz probe delay, we experimentally introduce a polar asymmetry in the pulse profile as high as 92%. To shape the spectrum, we apply the same technique after strongly chirping the Terahertz pulse. This led to significant reshaping of the spectrum with a 52% upshift of spectrum median. Pulse shaping techniques introduced here are of particular importance for temporal and spectral shape-sensitive THz nonlinear experiments. 
Mostafa Shalaby, Marco Peccianti, David G. Cooke, Christoph P. Hauri,   and Roberto Morandotti
physics.optics