The new device is part of a growing class of so-called metalenses—lenses less than a micron thick created from metasurfaces. These engineered surfaces have previously enabled unique optical properties in designs from flat optics to polarizers to holograms, but previous metalenses had fixed focal lengths. In the newly published work, the design combines liquid-crystal arrays with metalenses to create a system with multiple focal points.

The millimeter-scale lens, designed by researchers at Cornell and Samsung’s Advanced Institute of Technology, uses tiny silicon-based nanoparticles in a liquid-crystal cell. When a voltage is applied to electrodes sandwiching the cell, it causes the liquid-crystal molecules to align in a certain direction. The alignment affects the resonances of the nanoparticles, which changes the focus of the lens.