Dispersionless Phase Discontinuities for Controlling Light Propagation

Abstract

Ultrathin metasurfaces consisting of a monolayer of subwavelength plasmonic resonators are capable of generating local abrupt phase changes and can be used for controlling the wavefront of electromagnetic waves. The phase change occurs for transmitted or reflected wave components whose polarization is orthogonal to that of a linearly polarized (LP) incident wave. As the phase shift relies on the resonant features of the plasmonic structures, it is in general wavelength-dependent. Here, we investigate the interaction of circularly polarized (CP) light at an interface composed of a dipole antenna array to create spatially varying abrupt phase discontinuities. The phase discontinuity is dispersionless, that is, it solely depends on the orientation of dipole antennas, but not their spectral response and the wavelength of incident light. By arranging the antennas in an array with a constant phase gradient along the interface, the phenomenon of broadband anomalous refraction is observed ranging from visible to near-infrared wavelengths. We further design and experimentally demonstrate an ultrathin phase gradient interface to generate a broadband optical vortex beam based on the above principle.

A review of metasurfaces: physics and applications

“…A V-shaped antenna based metasurface has been used to create a vortex beam (i.e., Laguerre-Gaussian modes) from a Gaussian beam [12,65], resulting in optical singularity at the beam center and a helicoidal equal-phase wavefront carrying orbital momentum. Using a phase profile based on the Pancharatnam-Berry phase, a broadband phase plate generating optical vortex beams has been demonstrated using an array of rod antennas with different orientations 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 (see figure 4(c) and (d)) [46].…”

Ultra-thin, planar, Babinet-inverted plasmonic metalenses

“…[7][8][9][10][11][12][13][14] An array of such nanoantennas can form a metasurface to bend the light abnormally 7,8 in a fairly broad range of wavelengths and can create, for example, an optical vortex beam. 7,12 In addition, a metasurface arranged of plasmonic nano-antennas can be used as a very efficient coupler between propagating waves and surface waves.…”

Manipulating Smith-Purcell Emission with Babinet Metasurfaces

“…DOI: 10.1103/PhysRevLett.117.157401 Metasurfaces, two-dimensional metamaterials, have recently emerged as a new frontier of science because they provide large degrees of freedom to control over the propagation of light [1]. Metasurfaces allow us to tailor the phase, amplitude, polarization, and ray trajectory [2-4] of light based on a single layer of engineered structures or meta-atoms [5][6][7]. Conventional optical devices usually rely on phase accumulation over a long optical path due to the inherently weak interaction of light and matter.…”

“…Metasurfaces allow us to tailor the phase, amplitude, polarization, and ray trajectory [2][3][4] of light based on a single layer of engineered structures or meta-atoms [5][6][7]. Conventional optical devices usually rely on phase accumulation over a long optical path due to the inherently weak interaction of light and matter.…”