A multi-chip module (MCM) is described. This MCM includes two substrates having facing surfaces. Disposed on a surface of a first of these substrates, there is an optical waveguide, having an eigenmode in the plane of the surface, and an optical coupler, which redirects optical signals to and/or from the optical waveguide and a direction normal to the surface. Furthermore, disposed on a surface of a second of the substrates, which faces the surface of the first substrate, and which overlaps the optical coupler, there is an optoelectronic device. This optoelectronic device, which has an eigenmode in a direction perpendicular to the surface of the second substrate, selectively receives or provides the optical signal to and/or from the optical coupler. For example, the selective receiving or providing may be controlled by selectively applying a potential to the quantum-well device, thereby changing the optical properties of the optoelectronic device.