A characterization and detection method and system, the system comprising a terahertz beam source, a probe beam source, a detection crystal receiving a probe beam from the probe beam source and a terahertz beam from the terahertz beam source, the probe beam and the terahertz beam co-propagating collinearly through the detection crystal, and a polarizer analyser receiving the pump beam transmitted from the detection crystal, wherein the polarizer analyser comprises two liquid crystal variable retarders and a linear polarizer, the polarizer analyzer analyzing a phase delay and orientation changes of the principle axes of the probe beam induced by the THz electric field and polarization.