An apparatus includes a laser, an optical power combiner, and an electronic controller. The laser has a plurality of modulatable optical reflectors and is operable to emit mutually coherent optical beams from the modulatable optical reflectors. The optical power combiner has a first optical inputs connected to receive light of one of the optical beams emitted from a first of the modulatable optical reflectors and has a second optical input connected to receive light of one of the optical beams emitted from a second of the modulatable optical reflectors. The electronic controller is connected to operate the first and second of the modulatable optical reflectors to modulate the optical beams emitted therefrom to carry respective first and second data streams. The optical power combiner is connected to interfere the light received from the first and second of the modulatable optical reflectors with a relative phase difference.