An optical receiver has a monolithically integrated electrical and optical circuit that includes a substrate with a planar surface. Along the planar surface, the monolithically integrated electrical and optical circuit has an optical hybrid, one or more variable optical attenuators, and photodetectors. The optical hybrid is connected to receive light beams, to interfere light of said received light beams with a plurality of relative phases and to output said interfered light via optical outputs thereof. Each of the one or more variable optical attenuators connects between a corresponding one of the optical outputs and a corresponding one of the photodetectors.