Multifunctional active reflectarray metasurfaces (Conference Presentation)

Abstract

In the last several years, metasurfaces have demonstrated promise to control constitutive properties of light via interaction with nanoscale elements. Unlike the passive metasurfaces developed to date, actively controlled metasurface properties can enable the realization of new electrically-tunable low-profile optical components with numerous applications such as dynamic holograms, convergent lenses with reconfigurable focal lengths, and beam steering arrays, which are key requirements for future chip-based light detection and ranging (LIDAR) systems. In this work, we report a gate-tunable reflectarray metasurface, which can act as a focusing lens with reconfigurable focal length or as a beam steering device. This active reflectarray metasurface is actively controlled by use of indium tin oxide (ITO) as a material with voltage-tunable complex permittivity at 1550 nm operating wavelength. First, we experimentally demonstrate electrical control of the reflection phase and amplitude for metasurface unit elements, and we show that the phase shift of the metasurface unit element can be actively tuned from 0° to 300°. Our design enables independent electrical control of each metasurface element via individual application of the DC voltage. We also show that the same metasurface can exhibit multiple functionalities, acting both as a reconfigurable lens and a beam steering device.