AT&T Bell Labs scientists became interested in lightwave communication in the mid-1960s, when it became apparent that lightwaves had an enormous capacity for carrying information and were immune from electrical interference. Advances in lasers, light-emitting diodes, repeaters, connectors, photodetectors and glass fibers in the following decades - and the realization that they could be fabricated and installed as integrated components - led to the installation of the first lightwave system in an operating telephone company in 1977.

This installation was the world's first lightwave system to provide a full range of telecommunications service - voice, data, and video - over a public switched network. The system, extending about 1.5 miles under downtown Chicago, used glass fibers that each carried the equivalent of 672 voice channels.