Manipulating Free-space Optical Beams with a Silicon Photonic Mesh

Photonic integrated meshes made of tuneable interferometers enable implementation of functions programmable on demand and are being envisioned as the optical counterpart of electronic field programmable gate arrays. Several examples of photonic processors capable of performing arbitrary linear operations have been recently proposed, and are expected to find applications in different areas, from the on-chip processing of telecom signals to microwave photonics, and from quantum optics to neural networks. In this work, we use a reconfigurable mesh of silicon photonic Mach-Zehnder Interferometers (MZIs) to manipulate free-space optical beams. We demonstrate beam steering, beam coupling from a free-space optical source to a single mode waveguide and automatic identification of the direction of arrival of a beam from a free-space source.