An optical bus for interconnecting electronic devices. The bus has a substrate with through-holes therein. An optically conductive material is disposed on one side of the substrate. The material fills the through-holes and forms a layer of predetermined thickness on this side of the substrate. In the outer surface of this layer there are facets or angled regions. The surface and facets are optically reflective. Cards or modules are optically connected by means of optical connectors to the through-holes on the opposite side of the substrate. Light emitted by the connector travels to the associated faceted surface from which it reflects towards other faceted surfaces from which it is partially transmitted and partially reflected to another connector. The arrangement permits optical communication between a plurality of electronic devices.