BACK REFLECTION
EDFA Blooming:
The Fall of the Barricades
BY JOSÉ CHESNOY WITH CONTRIBUTION OF JACQUES AUGÉ 1. INTRODUCTION
I like to recall that three inventions have made the advent of long-haul optical communications possible since 1990: fused-silica fibers, semiconductor lasers, and last but not the least, Erbium Doped Fiber Amplifier (EDFA). The EDFA is one of the most revolutionary discovery in applied physics of the last three decades. It has enabled our present world of long-distance WDM fiber optics, and especially that of submarine cables. The global internet could not exist as it is today without it. Few technical breakthrough had such an impact in the life of our generations! One can refer to the basic book “Undersea Fiber Communication Systems” for a complete technical textbook about modern submarine cable technology [Ref.1] We had in a previous issue of SubTel Forum the keynote outstanding paper by Emmanuel Desurvire [Ref.2] who provided in his article the view of the key actor of the EDFA discovery in AT&T. In the present paper, I intend to show the other facet of the history: how it was lived by industrials who had to catch up in the shadow, with less traces behind them since their sole objective was to deliver products in time. Since the unexpected disruptive EDFA technology came out of the laboratory very suddenly –as a flower blooming- and became a “must have” for all industrials, one can imagine the effer-
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vescence to make the right industrial decisions for those who did not have initially in house the native genuine R&D activity on EDFA. An unknown facet of the introduction of EDFA is that it generated very violent internal battles inside companies since actors who made their carrier based on other technologies fought and raised barricades against the EDFA adventurers.
2. SHORT RECALL ON EDFA HISTORY
Rare earth in crystal or glass were well known laser medium in years 80. One just have to remember the Neodymium lasers used already since 20 years when scientists of the David Payne’s team in University of Southampton noticed in 1985-1986 [Ref.3] that Erbium, another rare earth, can be included in silica glass optical fibers with a fluorescence window in the 1.5 micron range that was the new 3rd window offered by silica fibers. The revealed invention of the EDFA took place when a solution was proven so that the Erbium can be included in clever conditions in specific optical fibers, and pumped optically by a low power semiconductor 1.48 micron laser made available and reliable through the semiconductor laser industrial programs. One can say that the invention was done through four key contributors: David Payne in University of Southampton, Emmanuel DESURVIRE and Randy
GILES in ATT Bell Labs, and Masataka NAKAZAWA in NTT. See Ref.2 for more details. This invention had the remarkable flavor to take only two years to move from a scientific esoteric topic to a major industrial proven breakthrough identified for its potential outstanding impact. It was ideal conditions for the original players to become monopolistic, but reality was just different as shown below.
3.THE “LEADERS” AND THE “FOLLOWERS”
Industrial companies have to make their R&D decisions and cannot keep leading on all topics. In years 1990, Alcatel was a leader in transmission, leading the SDH market and areas related to electronic signal processing. This competence had also permitted to become part of the leading teams of the new optical systems – submarine cables in particular – that were based on optical fibers and regenerated electronics (repeaters and terminals). But on the subject of EDFA research, AT&T was the leader, while all the other industrial players, between them Alcatel but also all European and Japanese players, were “followers”. Several conditions made possible the winning race of “followers” at that time: first patents were not yet used as key asset, and the leading industrial players let room open to their followers. Secondly, the competition was not as hard as after the deregulation, and