Velocity-matched generation of terahertz pulses in the organic crystal DAST

P Efficient generation of THz radiation through optical rectification is possible by using relatively long (-1 ps) optical pulses in materials with high second order susceptibilities when the group velocity of the optical pulse is matched to the phase velocity of all generated THz wavelengths. We show that these requirements are met by the organic salt DAST (4-N,N-dimethylamino-4'-N'methyl stilbazolium tosylate) which has already been shown to be a good THz emitter by rectification of sub-100 fs optical pulses [ I ] .