An optical assembly having x, y and z axes and comprising: (a) a first substrate having a planar surface, a first wall adjacent and substantially perpendicular to the planar surface, a first register surface adjacent the first wall, at least one foundation to receive an optical element having a first optical axis at least partially along the z axis; (b) an opto-electrical device (OED) having a top surface, an active area on the top surface having a second optical axis normal to the top surface, and a first alignment element defined on the top surface, the OED mounted to the first wall such that the first alignment element contacts the first register surface to position the OED on the first substrate along at least one of the x or y axes with the second optical axis parallel to the planar surface.