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Metasurface radome is crucial to protect the radiating antenna and control electromagnetic waves flexibly. However, current design methods for metasurface radome merely focus on the single propagation direction, with limited degrees of freedom. Here, a super radome is proposed with a directional scattering response based on Janus metasurface that can realize the phase modulation of y‐polarized waves and the amplitude modulation of x‐polarized waves with a judiciously designed structure. Both numerical and experimental results illustrate two cross‐polarized transmission windows with intensity exceeding 0.9 centered at 10 and 12.2 GHz and two out‐of‐band invisibility with considerable backward radar cross‐section reduction over −10 dB within 9.3–15.4 and 7.5–23.8 GHz when the radome is illuminated by y‐ and x‐polarized waves along negative and positive z directions, respectively. Moreover, the radar cross‐section reduction is maintained for off‐normal incidence even up to 45°. This method sets up a directional degree of freedom for advanced radome design and demonstrates its enormous potential in developing next‐generation stealth antennas. [ABSTRACT FROM AUTHOR]

Phonon polaritons provide useful opportunities, complementary to those provided by plasmon polaritons, in the study of the interaction of light with matter at small scales. The focus of this review is on phonon polaritons in low‐dimensional van der Waals (vdW) materials and heterostructures. Phonon polaritons confined in vdW materials exhibit large electromagnetic localization and are easy to hybridize with other collective modes. The extreme optical anisotropy in vdW systems produces the natural hyperbolic dispersion, enabling the access to deep subdiffractional optics and often yielding improved figures of merit over hyperbolic metamaterials. These virtues hold promises for practical nanophotonic applications, including optical sensing, super‐resolution imaging, energy and emission engineering, quantum optics, and a next generation of optical circuit elements. [ABSTRACT FROM AUTHOR]

Simultaneously independent control of phase, amplitude, and polarization is pivotal yet challenging for manipulating electromagnetic waves by transmissive metasurfaces. Huygens' metasurface affords a high‐efficiency recipe primarily by engineering phase‐only meta‐atoms, restricting itself from realizing unprecedentedly complex functions of the transmission beam. Here, a 3D chirality‐assisted metasurface concept relying on integrated magnetoelectric meta‐atoms is proposed. It empowers the completely decoupled and arbitrary control of phase and amplitude at large incident angles and arbitrary polarizations. This strategy thus facilitates very sophisticated beam manipulations at close‐to‐unity cross‐polarized efficiency via trilayer integrated resonators with mutual twist. The prescribed phase coverage can be determined by geometrical footprints of the unit cell, while the global azimuthal twist unlocks the capability of tuning amplitudes without affecting the phase. The concept and significance of it are validated to implement several proof‐of‐prototype demanding functionalities by thin metasurfaces of λo/12, which generate self‐accelerating diffraction‐free Airy beams, lateral and axial dual focusing, and even specific multiplexed beam shaping, respectively. This finding opens up an alternative way in very fine control of light with minimalist complexity and advanced performance. It can stimulate novel and high‐performance versatile photonic metadevices, thanks to the fully independent control of phase, amplitude, and polarization. The decoupling of amplitude, phase and polarization is analogous to the mechanical counterpart of three‐gear systems. The traditional dilemma is that tuning of either part will automatically affect the rest. This locks up metasurface functions and thereby limits its potentials. Now the authors' concept unlocks those "gears" such that each could be independently tuned, providing unprecedented access to the flatland of high‐efficiency metasurfaces. [ABSTRACT FROM AUTHOR]

High‐quality and tunable structural color printing with feasible fabrication is a key goal in recent decades, holding the possibility for full‐color microdisplay and impeccable cryptographic nanoprints. Plasmonic approach suffers from the inevitable material absorption restricting the color spectrum with suppressed lightness. Recent progress in dielectric nanophotonics offers low‐loss solution for color rendering, but dynamic functionality is still in infancy of changing colors with unchanged portraits, where more sophisticated physical mechanisms are in demand. Here, a strategy using full Kerker's conditions is reported to design low‐loss silicon metasurfaces which can generate broad spectrum of colors beyond the standard Red Green Blue (sRGB) gamut. The combination of the two Kerker's conditions enables dynamic and bright color palettes and full‐color microdisplay. Meanwhile, the asymmetric unit‐cell can guarantee polarization‐angle‐controlled reflective response with greatly sharpened spectra by complete control of the Kerker's effects. As a proof‐of‐concept, polarization‐encrypted images are demonstrated where completely distinguished pieces of information can be decoded exclusively only in predetermined polarization angle. They serve as highly‐secured cryptographic nanoprints that can be integrated with conventional smartphone technology. The complementary‐metal‐oxide‐semiconductor (CMOS)‐compatible metasurfaces can provide a new roadmap of anti‐counterfeiting tagging, advanced optical data storage, and tunable high‐contrast microprinting for real‐life applications. Polarization‐encrypted nanoprints are realized by tunable structural coloring with all‐dielectric metasurfaces. For the highly distinct colors, Kerker's conditions are applied to modulate the reflection spectra and near‐zero loss hydrogenated amorphous silicon is chosen. The demonstration of the nanoprints expands the scope of metasurfaces toward novel security technologies, and further shows their potential for integration with a variety of "Internet of Things" technologies. [ABSTRACT FROM AUTHOR]