Bell Labs Had Role in EDFA Development

The interesting recent article on Bell Labs, Lucent Technologies (Physics Today, October 2001, page 26 ), omitted an important detail. Although the article lists some of Bell Labs’ major achievements, including optical solitons, it does not mention erbium-doped fiber amplifiers (EDFAs). Despite their usefulness in improving our understanding of fiber nonlinearities and of new ways to exploit them, solitons have had only a limited impact on optical communications applications. EDFAs, however, have been key to enabling wavelength-division multiplexing technologies, broadband optical networks, and terabits-per-second terrestrial and undersea communications.

EDFAs were developed simultaneously at Southampton University and at Bell Labs, according to Herwig Kogelnik. ¹ His testimony is authoritative because he directed one of the two Bell Labs facilities in Crawford Hill, New Jersey, where the group of early EDFA investigators worked (1986–1990). The Crawford Hill investigations and demonstrations led to a rapid technology transfer to the Labs’ submarine-link department in Holmdel, New Jersey, and to several other development sites thereafter. (Research on solitons also benefited greatly from the transfer!) That transfer was the culmination of 20 years of fiber-optic research at Bell Labs and probably represents one of the company’s greatest success stories.

For my contribution to this early work, I received, jointly with the University of Southampton’s David N. Payne, the 1998 Benjamin Franklin Medal in Engineering. Yet, for unexplained reasons, Bell Labs never claimed its contribution to the invention and early development of EDFAs, despite their tremendous impact on technology and business. Such an anomaly, or memory erasure, shows that historical accuracy, even in famed institutions, can become secondary to internal rivalries (“not started in my department”) or marketing simplifications (“EDFAs have always been there”). True, practically all the early EDFA investigators have left the Labs, and the submarine group established its own company. But could this evolution justify censorship in Bell Labs’ history? The Labs should be proud of having been on the forefront of another technology revolution, thanks to the vision and risk-taking stance of both investigators and managers of Crawford Hill.

I recommend the National Academy of Sciences Web site, http://www4.nationalacademies.org/beyond/beyonddiscovery.nsf , which lists, under the Modern Communications menu item, pages titled “Basic Research Remains Vital” and “The Development of Lasers and Fiber-Optics—A Chronology of Selected Events.” Those state that Southampton University and Bell Labs discovered and developed “practical and effective” EDFAs.