Tunable and enhanced abrupt autofocusing of elliptical Airy beams using amplitude modulation.

Abstract

An elliptical Airy beam (EAB) offers a double autofocusing feature, which could be further improved by amplitude modulation through a hard, elliptical-shaped aperture. For this, we numerically study the propagation dynamics of the EAB after selectively blocking several rings consecutively. In each case, abrupt autofocusing is improved at both focal planes. However, the ellipticity of the beam influences the intensity contrast as well as the distance between both focal planes. Sequential blocking of rings also affects the focal position, depending on the ellipticity of the beam. When only the first ring of the EAB with small ellipticity is blocked, maximum intensity at the first focal plane remains almost the same. Therefore, better autofocusing ability can be achieved by only blocking the first ring. In addition, the impact of topological charge on the autofocusing is explored.