Spectral Characterization of a Terahertz Vortex Beam Generated Via a Two-Photon Lithography Printed Spiral Phase Plate

A terahertz (THz) vortex beam is generated through a spiral phase plate fabricated via two-photon polymerization lithography (TPL). TPL is a three-dimensional (3D) printing technique that exhibits high resolution and low surface roughness enabling the fabrication of high-frequency THz devices. The SPP is characterized via a scanless THz time-domain imaging (TDI) technique that allows to obtain a coherent hyperspectral analysis of the generated vortex beam. Numerical simulations are also conducted for comparison with experiments, revealing a good agreement.