Integrated Metasurfaces on Silicon Photonics for Emission Shaping and Holographic Projection

Abstract: The emerging applications of silicon photonics in free space, such as LiDARs and quantum photonics, urge versatile emission shaping beyond the capabilities of conventional grating couplers. A platform that offers arbitrary shaping of free-space emission while maintaining the CMOS compatibility and monolithic integration is in pressing need. Here we demonstrate a platform that integrates metasurfaces monolithically on silicon photonic integrated circuits. The metasurfaces consist of amorphous silicon nanopillars evanescently coupled to silicon waveguides. We demonstrate experimentally diffraction-limited beam focusing with a Strehl ratio of 0.82, where the focused spot can be switched between two positions. We also realize a meta-hologram experimentally that projects an image above the silicon photonic chip. This platform can add a highly versatile interface to the existing silicon photonic ecosystems for precise delivery of free-space emission.