Generation of terahertz vector beam bearing tailored topological charge

Abstract

Optical vector beams have great potential in many applications, for example optical tweezers, information transmission and processing, laser surface structuring, particle acceleration, and vortex dichroism spectroscopy. However, the reported vector beams in the terahertz (THz) spectral range are limited to exhibiting only low-order topological charges. Therefore, methodologies to generate THz vector beams bearing a tailored topological charge are highly desired. This work investigates how to generate THz vector beams with a tailored topological charge via the optical rectification process in a 111-cut ZnTe crystal pumped with a vector optical beam and how to manipulate the vector THz beam’s polarization state through the initial polarization angle. We theoretically and experimentally demonstrate that the transduction process produces a THz topological charge twice that of the infrared pump, also admitting the opposite sign. Given the well-developed technology to design infrared vector beams, the proposed method can generate THz vector beams with tailored topological charges.