Focusing properties of composite spiral photon sieve

Abstract

We aim to introduce and study a composite spiral photon sieve that is a photon sieve made of two independent and individual segments. Each segment has its characteristics, including hole density, diameter, and the number of spiral arms. We demonstrate that the element capable of producing a variety of optical vortex whose shape and structure is a function of the characteristic parameters. As an example, we show that by increasing the second segment’s weight, the produced vortex carrying topological charge “m” splits into “m” vortices of 1 topological charge. The other analysis demonstrates that by changing the hole density, both intensity and charge get modified. Moreover, further examinations illustrate that under certain conditions, an N-fold symmetry vortex beam is generated, which N equal to the absolute value of the difference between the number of spiral arms of the segments, and its charge is identical to the sum of the number of spirals’ absolute values of the segments. Finally, the simulation results are followed by the corresponding experiments to verify them.