Fig. 1: Multibeam FSO Receiver.
From: Separating arbitrary free-space beams with an integrated photonic processor
a Schematic of a 9 × 2 diagonal photonic processor comprising two rows of tunable MZIs and implementing a two-beam FSO receiver. The 2D optical antenna array is used to couple free-space beams into the silicon waveguides, while the output ports WG1 and WG2 are used to couple the light out to a pair of optical fibers. b Microscopic picture of the fabricated silicon chip. c Detail of the 2D optical antenna array made of 3 × 3 grating couplers in a square configuration. d Measured far-field pattern radiated by the 2D optical antenna array when all the grating couplers are excited with the same amplitude and phase. Multiple diffraction orders (grating lobes) are visible within the 5° × 9° angular beamwidth of the radiation pattern of the elementary grating coupler. e Detail of a thermally tunable beam coupler with a transparent monitor detector integrated at output ports. f Photograph of the photonic chip assembled on a PCB integrating the CMOS electronic ASIC for the read-out of on-chip detectors
