Revolutionary meta-imaging: from superlens to metalens

Abstract

The refractive-lens technique has been well developed over a long period of evolution, offering powerful imaging functionalities, such as microscopes, telescopes, and spectroscopes. Nevertheless, the ever-growing requirements continue to urge further enhanced imaging capabilities and upgraded devices that are more compact for convenience. Metamaterial as a fascinating concept has inspired unprecedented new explorations in physics, material science, and optics, not only in fundamental researches but also novel applications. Along with the imaging topic, this paper reviews the progress of the flat lens as an important branch of metamaterials, covering the early superlens with super-diffraction capability and current hot topics of metalenses including a paralleled strategy of multilevel diffractive lenses. Numerous efforts and approaches have been dedicated to areas ranging from the new fascinating physics to feasible applications. This review provides a clear picture of the flat-lens evolution from the perspective of metamaterial design, elucidating the relation and comparison between a superlens and metalens, and addressing derivative designs. Finally, application scenarios that favor the ultrathin lens technique are emphasized with respect to possible revolutionary imaging devices, followed by conclusive remarks and prospects.

An ultra-broadband solar absorber based on α-GST/Fe metamaterials from visible light to mid-infrared

“…19 The performance of metamaterials mainly depends on their structural characteristics, 20 rather than their material properties. 21,22 Metamaterials are used in many applications, such as invisibility cloaks, 23 superlenses, 24 negative refraction, 25 and solar cells. 26 Since Landy first proposed the concept of metamaterial perfect absorbers in 2008, the design ability of metamaterial absorbers has attracted attention and research interest from researchers in various fields.…”

Neural network assisted high-spatial-resolution polarimetry with non-interleaved chiral metasurfaces

“…Metasurface, a new emerging flat optical device, enables thin and lightweight optical elements with precisely engineered wavefronts [7][8][9][10] . Many innovative methods based on metasurfaces for polarimetry have been proposed.…”

Metasurfaces with Planar Chiral Meta-Atoms for Spin Light Manipulation

“…Increasing the number of meta-atoms with a high cross-polarization ratio (CPR) [21] is crucial for improving the phase modulation efficiency and signal-to-noise ratio of metasurfaces. For dielectric metasurfaces, it is evident that utilizing materials with high refractive index or increasing the aspect ratio of meta-atoms can expand the pool of meta-atoms with both high transmission and high CPR [4,27]. Nevertheless, the fabrication of meta-atoms with large aspect ratios poses a substantial challenge.…”

“…Nevertheless, the fabrication of meta-atoms with large aspect ratios poses a substantial challenge. Another method involves broadening the diversity of the basic shape of meta-atoms in searching for more appropriate shapes [27,28], which in turn increases the computational resource requirements. Consequently, there is a significant demand for identifying design restrictions on the basic shape to increase the quantity of highefficiency meta-atoms at a specific aspect ratio, which can shorten the optimization process.…”