An optical module is described. This optical module includes at least two optical devices that communicate with each other using edge-to-edge optical coupling of an optical signal between optical components in the two optical devices. Note that the edge-to-edge optical coupling may occur without mode converters at edges of either of the optical devices. Furthermore, the edge-to-edge optical coupling may be facilitated by an alignment substrate, which is mechanically coupled to the two optical devices. This alignment substrate aligns the edges of the two optical devices so that they are approximately parallel to each other, and aligns the optical components in the two optical devices.