Direct single-shot imaging of time-resolved terahertz vector fields

Abstract: We demonstrate direct single-shot retrieval of the full in-plane vector field of broadband terahertz waves using electro-optic sampling. Implemented with a circularly polarized optical probe and polarization-sensitive camera, the method overcomes the projection constraints of conventional electro-optic sampling and enables direct time-domain reconstruction of transverse vector fields without Fourier-domain inversion or sequential polarization analysis. We experimentally validate the approach through spatiotemporal imaging of linear, circular, azimuthal and radial terahertz fields generated by polarization-engineered silicon metamaterials. The measurements reveal ultrafast time-resolved vector-field dynamics inaccessible to conventional scalar detection, including helicoidal field rotation within a single optical cycle and the spatiotemporal evolution of structured polarization topologies. Beyond structured-field imaging, we demonstrate single-scan vector-field spectroscopy through measurements of quartz birefringence and broadband terahertz waveplate performance. More broadly, this work transforms electro-optic sampling from a projection-based measurement into a vector-resolved imaging and spectroscopy platform for structured electromagnetic fields.