Abstract: An optical pulse stream regenerator includes an optical receiver, a decision and timing circuit, and an optical transmitter. In response to an incident optical data pulse stream, a variable gain receiver section produces an electrical data pulse stream representing the incident optical data pulse stream. The receiver section is stabilized by having different variable gain devices respond to separate ranges of an automatic gain control signal. In response to the receiver section electrical data pulse stream, a phase-lock frequency-lock circuit in the timing circuit recovers a clock pulse stream that is synchronized with the incident optical data pulse stream, and the decision circuit regenerates an electrical data pulse stream representing the incident optical data pulse stream.

Abstract: A control circuit for an injection laser includes a driver circuit which applies a driving current to the laser in response to an electrical modulating signal. A prebias circuit applies a prebias current to the laser in response to the difference between a signal derived from the electrical modulating signal and a signal derived from the laser light output.

Abstract: An optical communication system is disclosed in which a bipolar signal of the type transmitted in digital transmission systems is converted into a unipolar binary signal for transmission over an optical transmission medium. The three levels of the bipolar signal are converted into three pairs of bits in the binary signal. One pair of bits is not utilized in the conversion and is therefore labeled as a forbidden word. Synchronization is achieved at the receiving location for the purpose of decoding by detecting the presence of the forbidden word in the binary signal and in response to this detection an energizing pulse is produced. This energizing pulse drives a clock circuit which in turn drives a decoding apparatus utilized to translate the binary signal back into the bipolar signal. As a result of this type of word synchronization, individual errors introduced into the binary signal do not result in a framing error.