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Temporal color mixing and dynamic beam shaping with silicon metasurfaces

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Science  19 Jul 2019:
Vol. 365, Issue 6450, pp. 257-260
DOI: 10.1126/science.aax5961

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A dynamic metasurface in the mix

Metasurfaces have been designed and fabricated to function as many passive optical elements. A time-dependent active element can now be obtained by marrying concepts in microelectromechanics with an array of one-dimensional dielectric nanowires. Although such a static array has been used to select for desired wavelengths, the wavelength is dependent on the nanowire-to-substrate separation. Holsteen et al. added a voltage-controlled actuation element to the design that could steer light beams as well as select and mix certain colors. The fast actuation capability could affect applications ranging from autonomous vehicles to augmented and virtual reality systems.

Science, this issue p. 257

Abstract

Metasurfaces offer the possibility to shape optical wavefronts with an ultracompact, planar form factor. However, most metasurfaces are static, and their optical functions are fixed after the fabrication process. Many modern optical systems require dynamic manipulation of light, and this is now driving the development of electrically reconfigurable metasurfaces. We can realize metasurfaces with fast (>105 hertz), electrically tunable pixels that offer complete (0- to 2π) phase control and large amplitude modulation of scattered waves through the microelectromechanical movement of silicon antenna arrays created in standard silicon-on-insulator technology. Our approach can be used to realize a platform technology that enables low-voltage operation of pixels for temporal color mixing and continuous, dynamic beam steering and light focusing.

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