Generating a perfect optical vortex: comparison of approaches

We derived exact analytical relationships to describe the complex amplitude of a perfect optical vortex generated by means of three different optical elements, namely, (i) an amplitude-phase element with the transmission function proportional to a Bessel function, (ii) an optimal phase element with transmission equal to the sign function of a Bessel function, and (iii) a vortex axicon. The doughnut intensity was shown to be highest when using an optimal phase element. The vortex-axicon-aided intensity ring was found to be about twice as wide as when generated using two other elements under analysis. Thus, the optimal filter was shown to be best suited for generating a perfect optical vortex. Simulation results were shown to corroborate theoretical predictions, with the experiment being in agreement with theory and simulation.