Electrically Reconfigurable Active Metasurface for 3D Distance Ranging

For the first time, we have successfully demonstrated a 3-dimensional (3-D) depth scan using an electrically-tunable active metasurface, which is an array of plasmonic resonators with an active indium-tin-oxide (ITO) layer. Our active device can steer a beam in reflection with a positive side-mode suppression ratio by independently controlling the amplitude and the phase from 0 to 360° using two separate bias controls. These are very promising results for small and high speed 3D depth sensing for mobile and automotive applications.

I. Introduction

The ability to control the amplitude and phase of incident light has enabled crucial applications such as 3-dimensional display, digital hologram, biomedical imaging, and light detection and ranging (LiDAR) for autonomous driving [1]. Recently, metasurfaces which are flat layers composed of optical nano-structures have been demonstrated to control the transmitted or reflected light in the subwavelength scale [2]. Active metasurfaces have attracted significant interest because of their potential for ultrafast, wide field-of-view and high-resolution wavefront shaping in a compact form. However, low phase modulation ranges below 360° [3]-[6] and amplitude-dependent phase change are the main hurdles for most application. Moreover, a large, individually addressable array of active metasurfaces with more versatility and flexibility have not yet been demonstrated in the optical regime. Here, we demonstrate distance measurement and 3-dimensional (3D) depth scan using a fully capable electrically active multi-channel metasurface in the near infrared (NIR) regime.