An optical interposer for optically coupling light between an OED supported on a substrate and an optical fiber, the interposer comprising: (a) an interposer of an optically-clear moldable material comprising at least the following features: (b) a port for receiving a ferrule containing at least one optical fiber, the port comprising an interface surface positioned to optically couple with an end face of the optical fiber; (c) an active lens adapted to optically couple with an OED, the active lens and the interface surface optically coupled along an optical path in the interposer; (d) a protrusion extending backward from the port, the protrusion defining a first register surface, the first register surface being a certain distance from the optical path such that, when a second register surface of a ferrule containing the optical fiber contacts the first register surface, the ferrule is aligned with the port such that the port can receive a front portion of the ferrule if the ferrule is pushed forward.