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

Abstract

which possess orbital angular momentum associated with helical phase-front. [3][4][5][6] Vector vortex beams (VVBs), as the name implies, possess the properties of both vector beams and vortex beams (i.e., with tailored phase and polarization distribution). The VVBs have been used for particle trapping, [7,8] optical communication, [9] quantum information, [10] high-resolution lithography, [11] etc. However, the applications of VVBs (as well as vortex beams) are limited as their annular intensity profiles vary with their topological charges [12] due to the incapable of amplitude control. This property may cause problems when compositing VVBs, as the intensity profiles of different VVBs cannot closely coincide with each other. To be specific, when the composited VVBs propagate, the state of polarization becomes unstable [13] and the intensity profile collapses, [14] which inevitably limits the co-propagation of multiple VVBs in optical system. Recently, Ostrovsky and co-workers [15] introduced the concept of perfect vortex beam (PVB), which has an annular intensity profile independent of topological charge. Plenty of methods to obtain the PVB have been proposed, such as using spatial light modulator, [15,16] axicon, [17] 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. The generation of PVVBs can be ultimately considered as the success of tailoring the APP of light. However, all these schemes to obtain the PVVBs and PVBs require a large number of bulky optical elements, which cannot be straightforwardly downsized, preventing widespread applications in miniaturized and integrated optical systems.Metasurface is planar structure that can locally manipulate the optical properties of light at subwavelength scales. [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. However, the generation of VVBs using metasurface cannot realize arbitrary polarization and phase distributions, and mostly of them are limited to linear polarization, [32][33][34][35][36] such as radially or azimuthally polarized beams. Most importantly, all the demonstrated VVBs based on metasurface are not perfect, that is, their annular intensity profiles are dependent on the topological charges.Vector vortex beams (VVBs) possess ubiquitous applications from particle trapping to quantum information. Recently, the bulky optical devices for generating VVBs have been miniaturized by using metasurfaces. Nevertheless, it is quite challenging for the metasurface-generated VVBs to possess arbitrary polarization and phase distributions. More critical is that the VVBs' annular intensity profiles demonstrated hitherto are dependent on topological charges and are hence not perfect, posing difficulties in spatially shared co-propagation of multiple vortex be...

Polarization Detection Using Light's Orbital Angular Momentum

“…[20,21] In 1992, it was recognized that light beams with a helical phase structure described by exp(iℓθ), where θ is the azimuthal angle and ℓ is the topological charge of optical vortex, carry an orbital angular momentum (OAM) of ℓℏ per photon. [22,23] Twisted light beams have been applied in various research fields, including optical communication, [3] optical trapping, [24] new forms of imaging systems, [25][26][27] nonlinear material, [28,29] and quantum optics. [30][31][32] As a promising candidate, optical metasurfaces have been used to generate various twisted light beams [33][34][35] and to control the superpositions of twisted light beams.…”

Multifunctional Beam Manipulation at Telecommunication Wavelengths Enabled by an All‐Dielectric Metasurface Doublet

“…[ 25 ] While the aforementioned metasurfaces were developed to serve single functions, multifunctional metasurfaces that can perform multiple tasks have attracted considerable interest owing to their potential use as multifocal or achromatic lenses, [ 26–28 ] metadevices serving distinct wave‐manipulation functionalities, [ 29–35 ] imaging systems, [ 36–38 ] nonlinear coding metasurfaces, [ 39–41 ] and vector vortex beam (VVB) generators. [ 42,43 ] For instance, metasurfaces in the visible or millimeter‐wave regime have been applied to implement VVB generators leading to vortex beams with different topological charges, with the assistance of unit cells consisting of multiple nanoblocks/layers with different geometrical parameters. [ 42,43 ] Meanwhile, single‐layered metasurfaces are inherently limited in terms of functional diversity.…”

“…[ 42,43 ] For instance, metasurfaces in the visible or millimeter‐wave regime have been applied to implement VVB generators leading to vortex beams with different topological charges, with the assistance of unit cells consisting of multiple nanoblocks/layers with different geometrical parameters. [ 42,43 ] Meanwhile, single‐layered metasurfaces are inherently limited in terms of functional diversity.…”

Full‐Color Complex‐Amplitude Vectorial Holograms Based on Multi‐Freedom Metasurfaces

“…In order to achieve this goal, we apply k ‐space engineering to split the different colored hologram images in different spatial locations and construct the full‐color image in a target area using grating dispersion (Figure 1c), which is much convenient than previous approaches requiring multiple incident angles. [ 31,32,47 ] We note that, there were also different approaches very recently [ 48,49 ] to independently modulate the phase, amplitude, and polarization based on the superposition of individual complex‐valued scattered fields of multiple resonators in each unit‐cells, although these design strategies are restricted to specific wavelengths and incident angles as well as implicit modulation relations.…”