Wideband Thin Film Modulators For Optical Communications

The development of optical modulators and switches is reviewed with emphasis placed on the comparison of conventional bulk modulators and thin film devices. It is shown that the primary motivation for such a development is the major reduction in the electrical drive power requirements for high bandwidth devices. The thin film devices are first discussed with acousto-optic and electro-optic devices in LiNb03 and LiTa03 given primary emphasis. The application of these devices to high speed scanning is shown to be quite promising. The problems of efficient coupling and optical power handling are shown to be important areas where improvements have been made. The development of directional couplers is then discussed with stress placed on the cross-talk performance and speed of the devices. The problem area of fiber-to-channel coupling is also discussed.