Full-color optical combiner based on multilayered metasurface design

摘要

Optical combiners are see through optical components, which fuse a virtual image with the real-world scene, and play akey part in near-to-eye (NTE) visors and head-up displays (HUDs). Several types of optical combiners have beendemonstrated in the past1,2. A common combiner scheme consists of a diffraction grating that couples light in and out ofa planar waveguide. This combiner is durable, relatively easy to manufacture, and can project high-resolution images.Projecting a full color image, however, is challenging due to large chromatic aberrations, and requires more complexdesign schemes. In this work, we present an optical combiner, which is based on a planar waveguide with embeddedmultilayered plasmonic metasurfaces, serving as achromatic diffractive grating couplers. The multilayered metasurfacegrating couplers are ultra-thin (<500nm) and highly transparent (～90%). We fabricated 1mmX1mm metasurface basedgratings using a standard E-beam lithography technique. The grating is designed to diffract only a specific wavelengthrange in the visible spectrum. Thus, it is possible to stack three layers of such metasurface gratings and couple a fullcolor (RGB) image into a single waveguide, while compensating for the inherent chromatic dispersion of diffractivegrating couplers.