Generation of Terahertz Superimposed Perfect Vortex Beams

A terahertz (THz) superimposed perfect vortex (SPV) beam is generated by using a designed superimposed optimal phase element (SOPE) at 0.3 THz. As the superimposed topological charge changes, the ring radius of THz SPV beams remains almost constant in the experiment, whose relative error is only 0.96%. The perfect vortex property is confirmed. The intensity profile of THz SPV beams is a ring with equally spaced breakpoints. The superimposed topological charge carried can be judged directly by identifying the number of breakpoints. The ring radius is linearly related to the radial wave vector, which can be adjusted. Such THz SPV beams have promising applications for THz fiber communication systems based on vortex beams.