Propagation effects in electro-optic sampling of terahertz pulses in GaAs.

Freely propagating terahertz pulses are detected in the time domain by electro-optic sampling in bulk GaAs. We investigate the influence of dispersion of the near-infrared sampling pulse on the transients by varying the thickness of the GaAs crystal. Pronounced propagation effects are identified that originate from the frequency dependence of the phase-matching condition between the terahertz and the sampling pulse.