Abstract: A multi-channel optical transmitter or transceiver includes transmitter optical subassembly (TOSA) modules optically coupled to and directly aligned with mux input ports of an optical multiplexer without using optical fibers. The optical multiplexer may include an arrayed waveguide grating (AWG) or a reversed planar lightwave circuit (PLC) splitter and may be located in a multiplexer housing having at least one side wall with input apertures aligned with the mux input ports. The TOSA modules may include a base supporting at least a laser, laser driving circuitry, and a lens for focusing the light output from the laser. Z-rings may be used to facilitate alignment and to mount the TOSA bases to the side wall of the multiplexer housing, for example, by laser welding.