Planar Meta-Optics

The control of phase plays a fundamental role in wave propagation. Metasurfaces (thin metamaterial layers) can introduce an additional spatially non-uniform phase in the incoming wave, thereby affecting its propagating characteristics. A metasurface consisting a plasmonic nano-antenna array can introduce an abrupt phase discontinuity at the interface and therefore have unparalleled wave-front control over the incident light. We experimentally demonstrate a computer generated hologram operating at a visible wavelength by a metasurface consisting of Babinet-inverted nano-antennas perforated on a 30-nm-thick gold film. Micrometer-sized metasurface lenses (metalenses) are made with the same technique.