A Free‐Space Orbital Angular Momentum Multiplexing Communication System Based on a Metasurface

Abstract

Optical vortex beams carrying orbital angular momentum (OAM) have received great attention since the 1990s. In particular, OAM offers an additional degree of freedom, thus, enabling boosting of data transmission capacity in communication systems. One of the major challenges of OAM-based communication lies in multiplexing OAM via a kind of effective, compact, and flexible approach. Here, a novel approach to achieve the generation and combination of OAM beams by a pre-engineered reflective metasurface chip is demonstrated. Compared to traditional methods of OAM generation, this approach shows superiorities of broadband operating wavelength, high mode purity, flexible design, and compact size. Moreover, a free-space OAM multiplexing communication experiment based on the single metasurface is successfully carried out, performing 448 Gbit s −1 data transmission with four different topological charges of OAM and two polarizations by 28-GBaud QPSK signals. This work experimentally demonstrates promising applications of the metasurface in high-capacity optical communication systems.

Terahertz Angle‐Multiplexed Metasurface for Multi‐Dimensional Multiplexing of Spatial and Frequency Domains

“…According to the conventional method to realize OAM multiplexing by different incident angles, [28][29][30][31] the frequency-dependent phase profile formula of the angle-multiplexed metasurface can be expressed as follows:…”

“…Recently, a method to realize OAM multiplexing by different incident angles based on a single metasurface is proposed. [27][28][29][30][31] This kind of metasurface provides different responses according to the illumination angle, which can be called an angle-multiplexed Figure 1. Concept of the method for OAM multiplexing represented by a 2D plane.…”

Optical Metasurfaces for Generation and Superposition of Optical Ring Vortex Beams

“…Recently, the OAM of light has attracted considerable attention as a new degree of freedom in a series of promising applications, such DOI: 10.1002/lpor.202000146 as optical tweezers, [1] multiplexers, and demultiplexers. [2][3][4] These developments have been triggering a revolution in optical communications based on OAM and SAM. There are many approaches to generating OAM beams, including diffractive optical elements [5] and spatial light modulators.…”

Direct routing of intensity-editable multi-beams by dual geometric phase interference in metasurface

“…Benefiting from the burgeoning capabilities for fabricating materials with accuracy geometries, metasurfaces consisting of subwavelength meta-atoms can elaborately tailor the amplitude, phase and polarization state of the interacting EM wavefront with the advantages of low profile, low loss, and simple fabrication, ranging from microwave to terahertz and optical regions [1][2][3][4][5][6]. Therefore, a plenty of applications have been implemented with metasurfaces, such as ultrathin metalens [3,4,[7][8][9][10], invisibility cloak [11,12], polarization converter [13,14], and vortex beam generator [15][16][17][18], etc.…”