Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities

Abstract

Thirty years ago, Coullet et al. proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex. Since then, optical vortices have been widely studied, inspired by the hydrodynamics sharing similar mathematics. Akin to a fluid vortex with a central flow singularity, an optical vortex beam has a phase singularity with a certain topological charge, giving rise to a hollow intensity distribution. Such a beam with helical phase fronts and orbital angular momentum reveals a subtle connection between macroscopic physical optics and microscopic quantum optics. These amazing properties provide a new understanding of a wide range of optical and physical phenomena, including twisting photons, spin–orbital interactions, Bose–Einstein condensates, etc., while the associated technologies for manipulating optical vortices have become increasingly tunable and flexible. Hitherto, owing to these salient properties and optical manipulation technologies, tunable vortex beams have engendered tremendous advanced applications such as optical tweezers, high-order quantum entanglement, and nonlinear optics. This article reviews the recent progress in tunable vortex technologies along with their advanced applications.

Maxwell Meets Marangoni—A Review of Theories on Laser‐Induced Periodic Surface Structures

“…[80][81][82] This was demonstrated by the use of socalled optical vortex beams, which allow to create focused laser beams with varying polarization states localized in complex spatial fluence distributions. [83] This is visualized in Figure 8, which Table 1. Classification of different types of LIPSS summarizing their characteristics (orientation to polarization, spatial period Λ), their qualitative representation in Fourier space, and the materials involved.…”

Experimental Demonstration of 11‐Dimensional 10‐Party Quantum Secret Sharing

“…[ 15 ] However, since polarization is limited to two dimensions, this implementation restricts scalability. Alternatively, the orbital angular momentum (OAM) [ 16,17 ] degree of freedom of light offers access to an infinite‐dimensional Hilbert space and is thus a promising candidate for scalable high‐dimensional quantum information processes. [ 18 ] Indeed, the OAM of light (scalar and vector) has been used to demonstrate the feasibility of high‐dimensional quantum cryptography over free‐space, [ 19–22 ] optical fiber [ 23,24 ] and underwater.…”

Topological Space‐Time Photonic Transitions in Angular‐Momentum‐Biased Metasurfaces

“…Therefore, the intensity pattern of an optical vortex shows a dark central spot in its cross section, whose radius increases by increasing the | l |. Recently, optical vortices have gained the attention of scientific community due to high‐dimensionality of Hilbert space of OAM modes and mutual orthogonality of distinct OAM states that can offer a wide range of applications [ 4,5 ] such as enhancing the channel capacity in communication systems, [ 6–8 ] super‐resolution and high‐contrast imaging devices, [ 9–11 ] optical tweezers, [ 11–13 ] multidimensional entanglement of photons, [ 14–16 ] and interferometry. [ 17,18 ] Several methods have been exploited to generate OAM‐carrying beams, [ 19 ] including spiral reflectors and phase plates, [ 20–23 ] ring antennas, [ 24,25 ] holographic diffraction gratings, [ 26,27 ] angular gratings, [ 28,29 ] trench waveguides, [ 30 ] and transformation optics.…”