Evolution of optical vortices in gradient media and curved spaces

Light propagation in gradient media and curved spaces induce intriguing phenomena, such as focusing and self-imaging, thus delivering a wide range of applications. However, these systems are limited to excitations without orbital angular momentum, which may produce unfore-seen results. Here, we demonstrate the reconstructions (or called imaging to some extent) of optical vortices (OVs) in two-dimensional (2D) gradient media and three-dimensional (3D) curved spaces. We present the evolution of OVs in two types of generalized Maxwell fisheye (GMFE) lenses from the perspective of geometrical and wave optics, and use coherent perfect absorbers (CPAs) to better recover the OVs in the converging position. Furthermore, we also demonstrate such phenomena in two types of 3D com-pact closed manifolds-sphere and spindle-which are also called geodesic lenses. Surprisingly, the results we obtained in 3D curved spaces can be seen as a strong verification of the Poincare-Hopf theorem. Our work provides a new, to the best of our knowledge, platform to investigate the evolution of OVs on curved surfaces.(c) 2023 Optica Publishing Group

Automated summary

This study demonstrates the reconstructions of optical vortices in gradient media and curved spaces, providing a new platform to investigate the evolution of optical vortices. The use of coherent perfect absorbers improves the recovery of optical vortices in the converging position. The results also verify the phenomena of optical vortices in ellipsoidal and spindle-shaped curved surfaces.