Slowing down or even stopping light is the first task to realising optical information transmission and storage. Theoretical studies have revealed that metamaterials can slow down or even stop light; however, the difficulty of preparing metamaterials that operate in visible light hinders progress in the research of slowing or stopping light. Metasurfaces provide a new opportunity to make progress in such research. In this paper, we propose a dendritic cell cluster metasurface consisting of dendritic structures. The simulation results show that dendritic structure can realise abnormal reflection and refraction effects. Single- and double-layer dendritic metasurfaces that respond in visible light were prepared by electrochemical deposition. Abnormal Goos-Hänchen (GH) shifts were experimentally obtained. The rainbow trapping effect was observed in a waveguide constructed using the dendritic metasurface sample. The incident white light was separated into seven colours ranging from blue to red light. The measured transmission energy in the waveguide showed that the energy escaping from the waveguide was zero at the resonant frequency of the sample under a certain amount of incident light. The proposed metasurface has a simple preparation process, functions in visible light, and can be readily extended to the infrared band and communication wavelengths.

3D metamaterials, has attracted considerable attention given its unique optical properties and produced many new phenomena and functionalities, such as plate focusing, [8] polarization conversion, [9] and mathematical operations. [10,11] The construction of these optical metasurfaces is generally a periodic arrangement of metal or dielectric micro-nanostructures. On the basis of the requirements, a plurality of the structural units with different geometric parameters (such as shape, size, and orientation) is arranged in an array to realize various kinds of abnormal optical responses. [12] However, few experimental reports are presented on periodic metasurfaces that respond in visible light. Cost remains high, large-area preparation remains challenging, and the deviation of the prepared structure is large, although tens of nanometer-sized structures can be prepared using complex electron beam-or ion beam-etching techniques, [13,14] thereby making periodic metasurfaces difficult to be extensively applied. The design requirement of periodic structures for the existing metasurfaces and top-down electron beam or ion beam etching technology, as well as the unidirectionality of optical response for the periodic metasurfaces, have become the bottlenecks that limit the rapid development of optical metasurfaces.Recently, researchers have used the Gerchberg-Saxton (GS) algorithm [15] to iterate a random-phase profile and obtain a disordered metasurface with a convergent-phase profile that manipulates the transmission of visible light and allows a farfield pattern to have isotropic scattering over a desired angular range. [16] To a certain extent, this method simplifies the preparation of optical metasurfaces. However, its structure must be prepared by electron beam lithography. Thus, this method does not completely solve the constraint that restrains the development of optical metasurfaces.Inspired by the idea of the GS algorithm, [15] we propose a quasiperiodic dendritic cluster set metasurface. In the simulation, the periodic metasurface tends toward the quasiperiodic metasurface by gradually changing the state of the dendritic structure in the periodic structural unit; in the bottom-up electrochemical deposition experiment, the disordered distribution of dendritic cluster sets tends toward the quasiperiodic distribution by continuously adjusting the preparation conditions. By gradually changing the theoretical model from a periodic structure to a quasiperiodic structure and the distribution of dendritic cluster sets in the sample from a disordered distribution Periodic metasurfaces have achieved various light manipulations. However, the preparation of those responding in visible waveband still encounters many constraints. Inspired by the idea of the Gerchberg-Saxton algorithm, a quasiperiodic dendritic cluster set metasurface is proposed where the cluster is used as the unit instead of cell that is used as the unit in the periodic metasurface. By gradually changing the theoretical model from periodic to quasiperiodic str...

Cross-polarization conversion plays an important role in visible light manipulation. Metasurface with asymmetric structure can be used to achieve polarization conversion of linearly polarized light. Based on this, we design a quasi-periodic dendritic metasurface model composed of asymmetric dendritic cells. The simulation indicates that the asymmetric dendritic structure can vertically rotate the polarization direction of the linear polarization wave in visible light. Silver dendritic cell-cluster metasurface samples were prepared by the bottom-up electrochemical deposition. It experimentally proved that they could realize the cross - polarization conversion in visible light. Cross-polarized propagating light is deflected into anomalous refraction channels. Dendritic cell-cluster metasurface with asymmetric quasi-periodic structure conveys significance in cross-polarization conversion research and features extensive practical application prospect and development potential.

Polarization is a property of transverse waves that specify the geometrical orientation of the oscillations, and it is of significant importance to control the polarization of waves at the information storage and processing. In this paper, we propose a new type of polarization conversion metasurface based on the [Formula: see text]-shaped structure in reflection mode. An ultrawideband cross-polarization conversion is obtained. The simulated results show that this metasurface can rotate the polarized direction of the linearly polarized electromagnetic wave by 90[Formula: see text] and the polarization conversion efficiency reaches up to 90% in the ultrawideband from 6.9 GHz to 22.2 GHz. The relative bandwidth is 105%. In addition, the experimental results of polarization conversion efficiency are in good agreement with the simulations. With the advantages of high conversion efficiency, ultrawide operating band and the simple geometric structure, the application of this polarization conversion metasurface structure can be extended to the frequency range of terahertz or even the visible light.

A quasiperiodic meta‐cluster metasurface model as an improved alternative to the previously published periodic meta‐cell metasurface model is proposed. Using a bottom‐up fabrication technique, isotropic visible metasurface samples are prepared based on the quasiperiodic dendritic meta‐cluster sets. Unusual optical phenomena including the anomalous spin Hall effect in the spectrum of red light and rainbow trapping effect are observed experimentally. More details can be found in article number https://doi.org/10.1002/admi.201801834 by Huan Chen, Jing Zhao, Zhenhua Fang, Di An, and Xiaopeng Zhao.