Square array of optical vortices generated by multiregion spiral square zone plate

Abstract

Herein, we present a so-called multiregion spiral square zone plate (MRSSZP), in which a spiral square zone plate is divided into a few regions, so that every region is composed of Fresnel zones, and the first zone of a given region is the same as the last zone of the previous region from a transmission point of view. We show that an MRSSZP can generate unique features of an array of an optical vortex with topological charge ±1, so that the number of vortices is directly related to the number of regions. We also demonstrate that, for an MRSSZP with topological charge 2, an array of dark cores is formed, which have phase structures similar to that of the interference of optical vortices with opposite topological charges. Besides, the focused vortex array follows a modulo-4 transmutation rule. In addition, when the topological charge becomes multiples of 4, an array of focal bright spots surrounded by a dark ring is generated. Numerical and experimental results verify the superior features of an MRSSZP.

Phase Singularities to Polarization Singularities

“…ere are many interference-based methods reported [71,[308][309][310][311][312][313] for vortex array generation in which multiple beams with non-coplanar propagation vectors are made to interfere. Vortex array generation by spiral Dammann zone plates [314] and spiral square zone plate [315] was also reported. 10.1.2.…”

Focus shaping of linearly polarized pseudo-nondiffracting beam using a radial shift and a large numerical aperture

“…The resulting element is called RSSZP which is created by modulating both a radial phase shift and a spiral zone plate phase. In addition, a type of square array of optical vortices, produced by a multi-regional square spiral zone plate (MRSSZP), has been introduced (Sabatyan et al 2016). More precisely, Sabatyan and Behjat (Sabatyan and Behjat 2017) have developed a new diffractive element for generating a perfect vortex beam using RSSZP.…”

Simple and efficient realization of transverse linear dark beams by azimuthal phase-shifted square zone plate

“…Hence, some techniques were proposed to improve its efficiency [16,17]. Furthermore, there have been reported some applications of SZP in, for example, infrared detectors [18], Cassegrain concentrator [19], solar energy systems [20], rectangle multi-array focusing [21], and unique rectangle array of structured beam [22].…”