1. An improved communications system employing electro-optical devices; said system comprising an integrated structure, said structure including very wide band gap, light transmissive conduit means and a plurality of active elements, each element including at least one layer of thin film amorphous silicon alloy material, said active elements distributed adjacent to and integrally formed with said conduit means; at least one of said elements adapted to project light signals within said conduit means in response to electrical signals applied thereto, and at least another one of said elements adapted to detect said light signals transmitted within said conduit means.