Abstract: An integrated-optical device including a substrate having waveguide and a plurality of electrodes to receive electrical signals for controlling the light transmission through the pathways. The waveguide pathways are in an interaction zone of an electro-optically active waveguide material whose refractive index changes in response to electrical signals applied to the electrodes, and also in an access zone providing optical access to the interaction zone. The active waveguide material in the interaction zone is preferably a different material from the waveguide material in the access zone, enabling improved performance and/or simpler fabrication in a number of described respects.

Abstract: An automatic gain control circuit 16 that can be used in a video transmission system 10 includes transmitter circuitry 18, receiver circuitry 20, and a fiber optic link 22 connected therebetween. The transmitter circuitry 18 injects an automatic gain control pulse having a known amplitude level into an electrical video signal. The transmitter circuitry 18 then converts the electrical video signal into an optical video signal, and transmits the optical video signal over the fiber optic link 22 to the receiver circuitry 20. The receiver circuitry 20 converts the optical video signal back into an electrical video signal and compares the amplitude level of the automatic gain control pulse in the electrical video signal to a reference having an amplitude level equal to the known amplitude level.

Abstract: A fiber optic extender system in which messages are transferred by fiber optic lines between remotely located electronic units. The electronic units (e.g., transformer-isolated) have three signal levels: positive voltage, negative voltage, and zero voltage. Because the fiber optic system can conveniently handle only two signal levels--on and off--potentially serious communication problems are avoided by generating and transmitting a short end-of-message pulse whenever the transmitting electronic unit is at zero voltage level. This end-of-message pulse is detected at the remote electronic unit, and the line is cleared for the next message.