High Capacity Lightwave Communications

There has been considerable progress in the telecommunications technology based on the transmission of lightwaves through optical fibers. Systems experiments in the 1.55 micrometer band have now demonstrated the capability of transmitting at rates as high as 4 gigabits per second over unrepeatered fiber lengths exceeding 100 kilometers. Elements of this progress are advances in the fabrication of low-loss single-mode fibers, in the spectral control of semiconductor junction lasers assuring single-frequency operation, and in high-speed detectors and receivers.