Terahertz vortex beam generation by infrared vector beam rectification

Abstract

We report on the conversion of an infrared vector beam into terahertz vortex beams using a ⟨110⟩-cut ZnTe cubic crystal. First, we provide a theoretical analysis demonstrating how an infrared vector beam with the azimuthal order ℓ can be transformed into a terahertz beam endowed with an orbital angular moment content that consists of optical vortices with topological charge ±2ℓ. Experimentally, quasi-monochromatic terahertz vortex beams with topological charges +2 and −2 are produced and characterized both in amplitude and phase using real-time two-dimensional imaging of the terahertz electric field. These results enrich the terahertz vortex beam toolbox via the transfer of topological information from the infrared to terahertz domains.