The first guided-wave components that employed signals in the form of light beams traveling along thin films were fabricated a little more than two decades ago. The parallel development of semiconductor lasers and the subsequent availability of low-loss optical fibers made possible the imple- mentation of completely optical systems for communications, signal pro- cessing and other applications that had used only electronic circuitry in the past. Referred to as integrated optics, this technology has been rein- forced by utilizing electronic components that act as controlling elements or...