Reconfigurable beam steering metasurface at telecommunication wavelengths (Conference Presentation)

Abstract

The ability to control all the important constitutive properties of light via interaction with nanoscale elements is a central concept in nanophotonics. In the last several years, metasurfaces have demonstrated promise as both flat optical elements to replace conventional three-dimensional components as well as to access functions that are unachievable in conventional optics. To date, the functional performance of metasurfaces has typically been encoded at the time of fabrication. However, active control of the properties of metasurfaces would enable dynamic holograms, focusing lenses with reconfigurable focal lengths, and beam steering, a key requirement for future chip-based light detection and ranging (LIDAR) systems. Here, we report the design and experimental demonstration of a continuous beam steering at telecommunication wavelengths using field-effect-tunable metasurfaces. The proposed beam steering device is actively controlled by incorporating indium tin oxide (ITO), as a material with voltage-tunable optical properties, into a metasurface. Using ITO as an active material and a composite hafnium-aluminum-oxide nanolaminate as the gate dielectric, we demonstrate a prototype tunable metasurface with a continuous phase shift from 0 to 300°. Our design enables independent control of each metasurface element via an individual application of DC voltage. This enables electrical control of the metasurface phase profile, which is an essential requirement for demonstration of continuous beam steering. By careful application of bias voltages to 96 biasing channels, we achieve a quasi-continuous beam steering with the steering angles of up to 75°.