Spatio-spectral full-Stokes mapping of broadband terahertz pulses

Abstract

We report a method for full-Stokes spatio-spectral characterization of broadband terahertz pulses from 0.5 to 2.5 THz. By combining two-dimensional electro-optic sampling with frequency-resolved Stokes analysis, we retrieve the complete polarization state of a terahertz field at each frequency component and at every point across the beam profile. This approach enables direct access to the spatially and spectrally resolved Stokes parameters, the associated degree of polarization, and the polarization ellipse parameters. We apply the method to characterize the terahertz birefringence of a quartz plate, revealing its frequency-dependent quarter- and half-wave behavior, and to map structured terahertz vector beams generated by a segmented quartz half-wave plate. Azimuthally and radially polarized terahertz vector beams are unambiguously identified through their spatial Stokes signatures, polarization azimuth distributions, and associated polarization singularities. This technique provides a versatile tool for broadband terahertz polarimetry and the investigation of complex polarization states in structured terahertz fields.