Generation of THz vector and scalar vortex beams by optical rectification along threefold symmetry axis in zinc blende crystals

Synthesis of THz frequency fields with generalized orbital angular momentum, the so called higher-order Poincaré beams are of interest to future communications systems and charged particle accelerators. We propose and demonstrate a route to generate and manipulate THz vector and scalar vortex beams using optical rectification by exploiting the threefold symmetry of the second-order susceptibility in zinc-blende crystals. In particular, we show that by shaping the pump beam using an S-waveplate, the order of the generalized angular momentum is doubled in the process of optical rectification. Moreover, we show that the generated THz vector vortex beam can be decomposed into two scalar vortex beams with opposite signs of angular momentum states. We show that the phases of these orthogonal states can be manipulated by simply tailoring the polarization state of the pump.