Generating and Separating Twisted Light by gradient–rotation Split-Ring Antenna Metasurfaces

Abstract

Nanoscale compact optical vortex generators promise substantially significant prospects in modern optics and photonics, leading to many advances in sensing, imaging, quantum communication, and optical manipulation. However, conventional vortex generators often suffer from bulky size, low vortex mode purity in the converted beam, or limited operation bandwidth. Here, we design and demonstrate gradient-rotation split-ring antenna metasurfaces as unique spin-to-orbital angular momentum beam converters to simultaneously generate and separate pure optical vortices in a broad wavelength range. Our proposed design has the potential for realizing miniaturized on-chip OAM-multiplexers, as well as enabling new types of metasurface devices for the manipulation of complex structured light beams.

Recent Progress in Far-Field Optical Metalenses

“…For instance, a plasmonic bipolar lens consisting of dipole nano-antennas with controlled directional orientation was designed to exhibit helicity-controllable real and virtual focal planes, as well as magnified and demagnified imaging at visible and near-infrared wavelengths [55]. We point out that, also, gradient-rotation split-ring antenna metasurfaces were designed and experimentally demonstrated as spin-toorbital angular momentum beam converters to simultaneously generate and separate pure optical vortices [56].…”

Coherent control of high efficiency metasurface beam deflectors with a back partial reflector

“…This relationship can be modified by introducing patterned dielectric/metal nanofilms at the boundary. 1 By properly designing these patterns as in a passive phased array antenna (namely, "metasurfaces (MSs)"), the nanofilms can be used to tailor the wavefront of the input light and obtain myriad functions such as beam-deflection/splitting depending on the polarization, 1-3 polarization conversion and generation, [4][5][6] holograms, 4,7,8 achromatic focusing lenses, [9][10][11][12] optical angular momentum beam conversion, 1,13 and pulse shaping. 14 However, in the case of beam deflectors, the beam deflection efficiency was somewhat low for the initial proposed design; only a small part of the input light (∼10%) can couple to the MS if there is only a single layer with a conventional MS structure on a dielectric substrate.…”

A Minimalist Single‐Layer Metasurface for Arbitrary and Full Control of Vector Vortex Beams

“…Recently, Ostrovsky and co-workers [15] introduced the concept of perfect vortex beam (PVB), which has an annular intensity profile independent of topological charge. [19,20] It has been widely used in many areas, including metalens, [21][22][23] holography, [24][25][26][27] vortex beams, [28][29][30][31] VVBs, [32][33][34][35][36][37] etc. By combining the generation methods of PVB with the Sagnac interferometer, perfect vector vortex beams (PVVBs) are also demonstrated, [18] which is able to possess stable state of polarization and intensity profiles upon propagation.…”

“…[19,20] It has been widely used in many areas, including metalens, [21][22][23] holography, [24][25][26][27] vortex beams, [28][29][30][31] VVBs, [32][33][34][35][36][37] etc. [19,20] It has been widely used in many areas, including metalens, [21][22][23] holography, [24][25][26][27] vortex beams, [28][29][30][31] VVBs, [32][33][34][35][36][37] etc.…”