Metasurface holograms reaching 80% efficiency

Abstract

Surfaces covered by ultrathin plasmonic structures--so-called metasurfaces--have recently been shown to be capable of completely controlling the phase of light, representing a new paradigm for the design of innovative optical elements such as ultrathin flat lenses, directional couplers for surface plasmon polaritons and wave plate vortex beam generation. Among the various types of metasurfaces, geometric metasurfaces, which consist of an array of plasmonic nanorods with spatially varying orientations, have shown superior phase control due to the geometric nature of their phase profile. Metasurfaces have recently been used to make computer-generated holograms, but the hologram efficiency remained too low at visible wavelengths for practical purposes. Here, we report the design and realization of a geometric metasurface hologram reaching diffraction efficiencies of 80% at 825 nm and a broad bandwidth between 630 nm and 1,050 nm. The 16-level-phase computer-generated hologram demonstrated here combines the advantages of a geometric metasurface for the superior control of the phase profile and of reflectarrays for achieving high polarization conversion efficiency. Specifically, the design of the hologram integrates a ground metal plane with a geometric metasurface that enhances the conversion efficiency between the two circular polarization states, leading to high diffraction efficiency without complicating the fabrication process. Because of these advantages, our strategy could be viable for various practical holographic applications.

Bifacial Metasurface with Quadrupole Optical Response

“…Metasurfaces are therefore more likely to find widespread technological applications. Recently demonstrated examples include holographic elements [23], lenses and axicons [24], antireflection coatings [25], mirrors [26], and polarization converters [27,28]. To our knowledge, however, a metasurface or a metamaterial with an electric-dipole-free optical response [29] and with a strong dependence of optical reflection on the illumination side [19] has not yet been demonstrated experimentally in the visible spectral range.…”

Analysis of a Waveguide-Fed Metasurface Antenna

“…In addition, if the metamaterial elements used to form the metasurface array are resonant, some phase delay is added to the radiated wave that can be controlled by tuning the resonances. This latter mechanism of controlling phase has been leveraged in the development of Huygen's metasurfaces [28][29][30] and metasurface holograms [31][32][33]. Even in cases where little or no additional phase shift is obtained from the elements, the metasurface aperture can nevertheless achieve high-quality beam forming and other wavefront shaping functionality by sampling the phase of the reference wave, often rivaling the performance of more advanced active antenna systems [1,19].…”

Characteristic Analysis of Compact Spectrometer Based on Off-Axis Meta-Lens

“…Compared with their traditional counterparts, metasurfaces have emerged as unparalleled devices to realize miniaturized, on-chip integrated and multifunctional optical systems [7][8][9][10]. Tremendous breakthroughs in the field of metasurface have given rise to expansive applications ranging from planar imaging lenses [8,9,[11][12][13][14], holograms [15][16][17][18][19], spectrometers [20,21], nonlinear devices [22,23] and even to invisible cloaks [24][25][26], etc.…”