An interposer comprising: (a) a planar substrate having top and bottom surfaces, said bottom surface defining at least one ferrule alignment structure, and one or more fiber bores extending from said bottom surface to said top surface, each fiber bore being in a certain position relative to said ferrule alignment structure and adapted to receive a fiber; (b) one or more lenses on or near said top surface, each lens aligned with one of said fiber bores; (c) at least one ferrule having an end face and comprising one or more fibers protruding from said end face, and at least one alignment feature cooperating with said ferrule alignment structure to position said ferrule precisely on said bottom surface such that said fibers are disposed in said fiber bores and are optically coupled with said lenses; and (d) at least one optical component having one or more optical interfaces and being mounted on said top surface such that each of said optical interfaces is aligned with one of said fiber bores and is optically coupled with one of said lenses corresponding to said one of said fiber bores.