An optical assembly includes a combination of laser sources emitting radiation, focused by a combination of lenses into optical waveguides. The optical waveguide and the laser source are permanently attached to a common carrier, while at least one of the lenses is attached to a holder that is an integral part of the carrier, but is free to move initially. Micromechanical techniques are used to adjust the position of the lens and holder, and then fix the holder it into place permanently using integrated heaters with solder.