Time-domain picture of the terahertz vector waveform measured by the electro-optic sampling method using the crystal symmetry

Interpretation of the vector waveform detected by using the electro-optic (EO) sampling method in the terahertz time-domain spectroscopy is presented, especially when there is a velocity difference between the elliptically-polarized terahertz pulse and the optical probe pulse in the EO crystal. The formulation can be used to interpret the time-domain vector waveform detected by the EO sampling method using the symmetry of the EO crystal without resorting to the polarizers.