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

Zhiyuan Xiang,Zhe Shen,Yaochun Shen

doi:10.1038/s41598-022-05017-0

Zhiyuan Xiang, Zhe Shen + Show 1 more

Open Access

https://doi.org/10.1038/s41598-022-05017-0

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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.

Highlights

Optical vortex (OV) can be used in the fields of optical manipulation and optical communication because of its inherent orbital angular momentum (OAM)
Where f indicates that the Q-Perfect vortex (PV) light field will be formed at the z = f plane, r, θ are the polar coordinates in the beam cross-section in the focal plane, δ(*) is the Dirac δ-function, l is the topological charge (TC) and r0 is the ring radius of the light field
As an alternative candidate to PV, our quasi- perfect vortices (Q-PVs) was produced based on PB phase metasurface, it can be regarded as an annular light field with vortex phase gradient

Summary

Introduction

Optical vortex (OV) can be used in the fields of optical manipulation and optical communication because of its inherent orbital angular momentum (OAM). 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. Optical vortex (OV) as a kind of Laguerre-Gaussian (LG) mode beam with spiral phase and orbital angular momentum (OAM), has main applications in the fields of particle trapping and manipulation[1,2,3] and optical communication[4,5,6]. PV has been generated by using conical lens to generate annular beam and SLM to mark vortex phase, and it has been used to achieve fixed orbit OAM manipulation in the tight focal field[25]. In 2018, Yang combined these phases on one single plasmonic metasurface based on PB phase to obtain a 3D broadband PV33

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