Focoplaatarrays

Focoplaatarrays are a conceptual class of planar metamaterial assemblies designed to control the phase of incident electromagnetic waves across a surface.

A typical foco plaat array consists of a repeating unit cell formed by a thin plate bearing a subwavelength pattern. Plates can be dielectric, metallic, or layered composites and are fabricated on rigid or flexible substrates using lithography, etching, nanoimprinting, or deposition techniques. The spacing, alignment, and pattern geometry define the local phase delay each cell imparts.

The operating principle relies on constructive and destructive interference across the array, producing a prescribed phase profile with a relatively thin form factor compared with conventional lenses. By tuning plate geometry and material properties, the device can be engineered to operate over a range of frequencies from microwaves to infrared.

Potential applications include flat or ultrathin lenses known as metalenses, beam steering in antenna or LiDAR systems, holographic displays, and compact imaging sensors. Advantages include reduced thickness and weight and potential for large-area fabrication; limitations involve material losses at higher frequencies, angular sensitivity, and fabrication complexity at small scales.

They are related to metasurfaces and metamaterials and are the subject of ongoing research in optical and radio-frequency engineering.