The spatial redistribution of the orbital angular momentum quantum number in an optical vortex array

Abstract

Orbital angular momentum (OAM) and structured light have attracted significant attention in quantum optics and quantum information science by providing novel degrees of freedom and high-dimensional Hilbert spaces. Such OAM of light is conventionally controlled by digital or mechanical devices such as spatial light modulators, digital micromirror devices, and q-plates. However, OAM can be generated from a very fundamental optical phenomenon: interference. The interference of three or more light fields can generate an optical vortex array (OVA) formed by positive and negative unit vortices. In this work, we investigate the evolution of OAM and the underlying phase structure of an OVA consisting of a vortex beam and Gaussian beams. In the interference region, higher-order OAM is split into unit vortices while conserving the net OAM quantum number. For fractional OAM, the number of unit vortices follows the topological charge of the total field. Our findings provide a fundamental understanding of the OAM of light, offering valuable physical insights for high-dimensional state manipulation in quantum information processing.