Generation of radially- and azimuthally-polarized terahertz cylindrical vector beams from spintronic terahertz emitter

Generation of cylindrical vector beams (CVBs) [1] , namely the radially- and azimuthally-polarized light, in the terahertz (THz) region has gained significant interest as the focal properties of CVBs offer numerous potential applications in THz spectroscopy and imaging etc. Although various generation methods have been proposed to this date, most rely on complex experimental techniques and/or extremely high intensity of laser pulses. Recently, a spintronic THz emitter has emerged as a new class of highly-efficient THz source for table-top experiments [2] , and it has been proposed that its controllability of polarization by tailoring external magnetic field provides a quadrupole-like electric field pattern [3] . In this work, we report a simple methodology using a spintronic THz emitter of generating azimuthal and radial polarizations which combines appropriate design of magnetic field and mode conversion.