Quasi-perfect vortices generated by Pancharatnam-Berry phase metasurfaces for optical spanners and OAM communication

Abstract

Optical vortex (OV) can be used in the fields of optical manipulation and optical communication because of its inherent orbital angular momentum (OAM). The size of the OV ring increases with the correlated topological charge (TC), making the OV with large TC not suitable for optical rotation and short-distance communication. Perfect vortex (PV) has attracted much attention due to that its optical transmission profile is almost independent of TC. In this manuscript, we proposed a method to generate quasi- perfect vortices (Q-PVs) by Pancharatnam–Berry (PB) phase metasurfaces, the so-called Q-PV can be regarded as an annularly focused optical vortex whose focal ring in the focal plane has an angular phase gradient. It has a similar property to PV in that its light profile hardly changes with TC in the focal plane. We demonstrated that the Q-PV can be used for optical spanners that particles are trapped and rotated on the specific orbit. Non-coaxial and coaxial Q-PV arrays were further generated for OAM communication applications. We believe that the proposed Q-PVs has potential applications in optical manipulation and optical communication.

Metasurface-Incorporated Optofluidic Refractive Index Sensing for Identification of Liquid Chemicals through Vision Intelligence

“…A doughnut-shaped vortex beam was vividly generated in the air at a focal length of 200 μm. The size of the beam on the focal plane can be governed by the topological charges, which reflect the linear relationship between the beam size and optical angular momentum l. 34 Accordingly, a topological charge of five was required to deliver a relatively large vortex beam spot from the perspective of vision intelligence-based in situ liquid identification. Based on a series of rigorous simulations, the proposed metasurface was manufactured via electron beam lithography, as illustrated in Figure S2a and detailed in the Methods.…”

Research Progress on Router Devices for the OAM Optical Communication

“…Due to the existence of a phase singularity in the center of the beam, the distribution of the vortex annular field intensity is 0. This type of beam is commonly referred to as an OAM beam or vortex beam [19][20][21][22][23]. The helical phase structure characteristics of a vortex beam are determined by the phase factor exp(ilφ), [24][25][26].…”

Optical pulling of dielectric particles with non-paraxial Bessel beams through Pancharatnam-Berry metasurfaces

“…Metasurface devices alleviate these problems. Metasurfaces have the ability to flexibly adjust the phase locally, and can add additional phase gradients [25] or the phase of optical vortices [26] to the initial phase profile. Such devices have good prospects for miniaturization and integration.…”