A metasurface is an artificial nanostructured interface that has subwavelength thickness and that manipulates light by spatially arranged meta-atoms—fundamental building blocks of the metasurface. Those meta-atoms, usually consisting of plasmonic or dielectric nanoantennas, can directly change light properties such as phase, amplitude, and polarization. As a derivative of three-dimensional (3D) metamaterials, metasurfaces have been emerging to tackle some of the critical challenges rooted in traditional metamaterials, such as high resistive loss from resonant plasmonic components and fabrication requirements for making 3D nanostructures. In the past few years, metasurfaces have achieved groundbreaking progress, providing unparalleled control of light, including constructing arbitrary wave fronts and realizing active and nonlinear optical effects. This article provides a systematic review of the current progress in and applications of optical metasurfaces, as well as an overview of metasurface building blocks based on plasmonic resonances, Mie resonance, and the Pancharatnam-Berry phase.

We show that a metasurface-coated two-dimensional (2D) slab waveguide enables the generation of arbitrary complex light fields by combining the extreme versatility and freedom on the wavefront control of optical metasurfaces with the compactness of photonic integrated circuits. We demonstrated offchip 2D focusing and holographic projection with our metasurfacedressed photonic integrated devices. This technology holds the potential for many other optical applications requiring 2D light field manipulation with full on-chip integration, such as solid-state LiDAR and near-eye AR/VR displays.

Metalenses promise potential for a paradigm shift of conventional optical devices. However, the aperture sizes of metalenses are usually bound within hundreds of micrometers by the commonly used fabrication methods, limiting their usage on practical optical devices like telescopes. Here, for the first time, we demonstrate a high-efficiency, single-lens, refractive metalens telescope. We developed a mass production-friendly workflow for fabricating wafer-scale (80 mm aperture) metalenses using deep-ultraviolet (DUV) photolithography. Our metalens works in the near-infrared region with nearly diffraction-limited focal spot sizes and a high peak focusing efficiency of 80.84% at 1450 nm experimentally. Based on the metalens, we built a single-lens telescope and acquired images of the lunar surface, revealing its geographical structures. We believe our demonstration of the metalens telescope proves the exciting potential lying in the metasurfaces and could bring new possibilities for areas involving large optical systems, including geosciences, planetary observation, and astrophysical science.

Traveling-wave electro-optic modulators based on chromophoric self-assembled superlattices ͑SASs͒ possessing intrinsically polar microstructures have been designed and fabricated. Although the thickness of the SAS layer is only ϳ150 nm, a-phase shift is clearly observed. From the measured V value, the effective electro-optic coefficient of the SAS film is determined to be ϳ21.8 pm/V at an input wavelength of 1064 nm.

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