MEMS-based variable metasurfaces to control the direction and color of light

Abstract

Actively tunable metasurface have been of interest after recognition of the importance of un-natural response of metasurfaces. Micro-electro-mechanical system(MEMS) have obtained attention as the component which gives tunability to metasurfaces because of its reliable movement and high speed. However, for visible and near-infrared regime, since the wavelength is too small, a complex structure with subwavelength dimension is difficult to be realized generally. In this study, the possibility of combination of MEMS and metasurface for visible and near-infrared regime is investigated in terms of amplitude and phase control, which is the representative characteristic of a light. As part of the amplitude control, color switches are proposed and analyzed. By controlling the mechanical displacement, this device can pass a range of wavelength(color) or block all light(dark). As part of the phase control, beam-steering metasurface is proposed. This device is designed to steer normally incident beam into the direction we want using Gires-Tournois etalons as resonators. With appropriate design of unit cells, MEMS can be used in a variety of field such as energy-efficient display, light detection and ranging(LiDAR) for autonomous car and many other devices.