An apparatus includes a connector that connects to optical fibers for connecting first and second optical signals to the apparatus. A first optical ferrule is mounted perpendicularly to the connector, and transfers the first optical signals between the connector and first optical transducers mounted on a first substrate, via first holes formed in the first substrate. A second optical ferrule is mounted perpendicularly to the connector, and transfers the second optical signals between the connector and second optical transducers mounted on a second substrate, via second holes formed in the second substrate. A light rotation module bends and transfers the first and second optical signals between the connector and the first and second ferrules. One or more lenses are mounted between the first ferrule and the first holes, so as to couple the first optical signals via the first holes between the first ferrule and the first optical transducers.