Amplitude-phase imaging of pulsed broadband terahertz vortex beams generated by spiral phase plate

We present a simulation-based and experimental study propagating broadband terahertz vortex beams generated by a spiral phase plate. Numerical simulation based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the broadband (0.1 to 2.5 THz) vortex beam at different distances from the spiral phase plate. For experimental studies, THz pulse time-domain holography was applied to retrieve spatial amplitude and phase distributions of propagating vortex beams.