An optical multiplexer and methods of making and calibrating the same are disclosed. A method of aligning components in a multichannel optical/optoelectronic transmitter includes passively fixing a plurality of light emitters in place on a substrate; adjusting positions of a first lens passing light from a first light emitter and an optical signal transmission medium receiving the light from the first light emitter until a far field spot of the light from the first light emitter is at or near an end of the transmission medium; fixing one or more optical subassemblies on the substrate; and adjusting positions of the optical subassembly(ies) to align light from the remaining light emitters with the far field spot. Some embodiments include multiple optical subassemblies, each including a lens and a filter. Other embodiments include one optical subassembly including a mirror and a beam combiner.