Ultra-Compact Silicon Photonic Interface for Satellite-to-Ground Downlinks

An ultra-compact array of optical antennas based on vertically coupled grating couplers has been designed to enable optical coupling with low geometrical losses. The array is followed by meshes of phase shifters and a binary tree of optical combiners to compensate for the phase fluctuations imposed on the beam’s wavefront due to atmospheric turbulence. The chip works as an intermediate level between free-space optics and fiber-based networks for satellite-to-ground downlinks and terrestrial optical wireless applications at 1550 nm wavelength.