Optical metasurfaces for beam scanning in space.

The concept of a layered metasurface constructed from loop nanoantennas for beam scanning in space is explored. Each layer of the metasurface can be envisioned as a shunt impedance sheet designable by modifying the loop configuration cell by cell. The single and concentric loop nanoantennas made of silver provide capacitive and inductive impedances, respectively, with negligible loss at 1.5 μm, managing full control of the beam phase and amplitude. A telecom metasurface for beam scanning in 3D space is presented. The complex structure is modeled with an in-house-developed finite-difference time-domain method considering interactions among elements, in contrast to many designs in which isolated elements are simulated by assuming local periodicity.