Dielectric gradient metasurface optical elements

• Published in: Science (American Association for the Advancement of Science) Vol. 345; no. 6194; pp. 298 - 302
• Main Authors: Lin, Dianmin, Fan, Pengyu, Hasman, Erez, Brongersma, Mark L.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 18.07.2014; The American Association for the Advancement of Science
• Subjects: Boundary layer; Chemical elements; Construction; Devices; Dielectric materials; Dielectrics; Diffraction gratings; Light; Light beams; Miniature; Nanostructure; Optical components; Optical lenses; Optical properties; Optical resonance; Patterning; Radio antennas; Semiconductors; Silicon; Transmission efficiency; Wave diffraction; Wavelengths
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1253213

Gradient metasurfaces are two-dimensional optical elements capable of manipulating light by imparting local, space-variant phase changes on an incident electromagnetic wave. These surfaces have thus far been constructed from nanometallic optical antennas, and high diffraction efficiencies have been limited to operation in reflection mode. We describe the experimental realization and operation of dielectric gradient metasurface optical elements capable of also achieving high efficiencies in transmission mode in the visible spectrum. Ultrathin gratings, lenses, and axicons have been realized by patterning a 100-nanometer-thick Si layer into a dense arrangement of Si nanobeam antennas. The use of semiconductors can broaden the general applicability of gradient metasurfaces, as they offer facile integration with electronics and can be realized by mature semiconductor fabrication technologies.