Dielectric gradient metasurface optical elements

Extending the range of planar optics To build miniature optical devices, scientists are using silicon to replace bulky three-dimensional devices with flat versions. A patterned surface consisting of dense arrays of nanoscale silicon strips, which act as antennae, can be designed to work as transparent optical devices for the manipulation of light. Lin et al. used their versatile patterning technique to create a suite of planar optical elements. By patterning a 100-nm layer of silicon into a dense arrangement of nano-antennae, they were able to fabricate gratings, lenses, and axicons—a device that can add a shape to a propagating light beam. Science , this issue p. 298