A Reusable Metasurface Template

Perovskite single-pixel detector for dual-color metasurface imaging recognition in complex environment

Highly efficient multi-dimensional data storage and extraction are two primary ends for the design and fabrication of emerging optical materials. Although metasurfaces show great potential in information storage due to their modulation for different degrees of freedom of light, a compact and efficient detector for relevant multi-dimensional data retrieval is still a challenge, especially in complex environments. Here, we demonstrate a multi-dimensional image storage and retrieval process by using a dual-color metasurface and a double-layer integrated perovskite single-pixel detector (DIP-SPD). Benefitting from the photoelectric response characteristics of the FAPbBr2.4I0.6 and FAPbI3 films and their stacked structure, our filter-free DIP-SPD can accurately reconstruct different colorful images stored in a metasurface within a single-round measurement, even in complex environments with scattering media or strong background noise. Our work not only provides a compact, filter-free, and noise-robust detector for colorful image extraction in a metasurface, but also paves the way for color imaging application of perovskite-like bandgap tunable materials.

Light-Matter Interactions in Hybrid Material Metasurfaces

This Review focuses on the integration of plasmonic and dielectric metasurfaces with emissive or stimuli-responsive materials for manipulating light-matter interactions at the nanoscale. Metasurfaces, engineered planar structures with rationally designed building blocks, can change the local phase and intensity of electromagnetic waves at the subwavelength unit level and offers more degrees of freedom to control the flow of light. A combination of metasurfaces and nanoscale emitters facilitates access to weak and strong coupling regimes for enhanced photoluminescence, nanoscale lasing, controlled quantum emission, and formation of exciton-polaritons. In addition to emissive materials, functional materials that respond to external stimuli can be combined with metasurfaces to engineer tunable nanophotonic devices. Emerging metasurface designs including surface-functionalized, chemically tunable, and multilayer hybrid metasurfaces open prospects for diverse applications, including photocatalysis, sensing, displays, and quantum information.

Artificial Intelligence in Meta-optics

Recent years have witnessed promising artificial intelligence (AI) applications in many disciplines, including optics, engineering, medicine, economics, and education. In particular, the synergy of AI and meta-optics has greatly benefited both fields. Meta-optics are advanced flat optics with novel functions and light-manipulation abilities. The optical properties can be engineered with a unique design to meet various optical demands. This review offers comprehensive coverage of meta-optics and artificial intelligence in synergy. After providing an overview of AI and meta-optics, we categorize and discuss the recent developments integrated by these two topics, namely AI for meta-optics and meta-optics for AI. The former describes how to apply AI to the research of meta-optics for design, simulation, optical information analysis, and application. The latter reports the development of the optical Al system and computation via meta-optics. This review will also provide an in-depth discussion of the challenges of this interdisciplinary field and indicate future directions. We expect that this review will inspire researchers in these fields and benefit the next generation of intelligent optical device design.

Simultaneous and independent regulation of circularly polarized terahertz wave based on metasurface

A single metasurface-based device possessing multiple functionalities is highly desirable for terahertz technology system. In this paper, we design a reflective metasurface to generate switchable vortex beams carrying orbital angular momentum (OAM), focusing beams, focusing beams with arbitrary positions, and vortex beams with arbitrary topological charges in the terahertz region. By combining the spin decoupling principle and the phase addition theorem, the superposition states of OAM and focusing beams with arbitrary positions can be independent manipulated under right-handed and left-handed circularly polarized (LCP/RCP) waves illumination. Such a diversified functionalities device provides a promising application in the field of terahertz communication and terahertz super-resolution imaging.

Optical Fireworks Based on Multifocal Three-Dimensional Color Prints

Colorful three-dimensional (3D) prints are promising as practical anticounterfeiting labels with easily recognizable and striking visual effects. However, existing colorful 3D displays either require specific illumination conditions with multiple coherent lasers, hence suffer from speckles, or are unsuitable as passive labels. Here, we report a concept of a virtual 3D color object consisting of colorful focal spots in free space. The colors and corresponding "floating heights" of these spots are independently controlled via the design of 3D printed microlens profiles and heights of nanopillars that act as structural-color filters. Despite the unremarkable appearance of the printed substrate under both optical and electron microscopy, illumination with incoherent white light reveals information in the form of bright colorful spots appearing at designated heights above the plane of the substrate. The term "optical fireworks" refers to the way these spots appear and disappear under an optical microscope as one continuously shifts the focal plane. Our 3D printed optical fireworks security labels introduce applications for optical elements integrated with nanostructures in 3D colorful displays and anticounterfeiting labels.

Design of Multifunctional Janus Metasurface Based on Subwavelength Grating

In this paper, a Janus metasurface is designed by breaking the structural symmetry based on the polarization selection property of subwavelength grating. The structure comprises three layers: a top layer having a metallic nanostructure, a dielectric spacer, and a bottom layer having subwavelength grating. For a forward incidence, the metal-insulator-metal (MIM) structure operates as a gap plasmonic cavity if the linearly polarized (LP) component is parallel to the grating wires. It also acts as a high-efficiency dual-layer grating polarizer for the orthogonal LP component. For the backward incidence, the high reflectance of the grating blocks the function of the gap plasmonic cavity, leading to its pure functioning as a polarizer. A bifunctional Janus metasurface for 45 degrees beam deflector and polarizer, with a transmission of 0.87 and extinction ratio of 3840, is designed at 1.55 μm and is investigated to prove the validity of the proposed strategy. Moreover, the proposed metasurface can be cascaded to achieve more flexible functions since these functions are independent in terms of operational mechanism and structural parameters. A trifunctional Janus metasurface that acts as a focusing lens, as a reflector, and as a polarizer is designed based on this strategy. The proposed metasurface and the design strategy provide convenience and flexibility in the design of multifunctional, miniaturized, and integrated optical components for polarization-related analysis and for detection systems.