Remembering the
Million-Hour
L ASER

Richard W. Dixon

Bell Labs/Alcatel-Lucent, courtesy AIP Emilio Segrè Visual Archives, Hecht Collection

In the early 1970s, it was clear to the scientists at Bell Labs that light propagating in fiber waveguides could transmit large volumes of data over long distances. Semiconductor lasers were, in principle, nearly ideal sources—but they were riddled with performance and reliability problems. On the 50th anniversary of the diode laser, Richard Dixon reminisces about the program that took the device from laboratory curiosity to the applied technology that forms the backbone for terrestrial and undersea communications.

n the late 1960s, Bell Labs had a problem. The nation’s demand for long-distance telecom-
munications services was steadily increasing, but the technologies then in use—coaxial
cable and point-to-point microwave transmission through the air—could not keep up with
the pace. Bell mounted a considerable effort to explore a precision low-loss millimeter-wave pipe
for this expansion purpose, including the design, production and installation of several miles of
buried pipe to test the concept in the field—but the results were discouraging. Technically the
pipe could be made to work, but it would clearly be very expensive and cumbersome to install
and maintain. Thus, the company was primed to consider other alternatives.

The major reductions in optical fiber waveguide losses reported in the early 1970s were therefore of great interest. The lowest loss regions of these fibers were in the 0.8 to 0.9 µm range—which could in principle be accessed by devices built using the GaAs-Ga AlAs material system. Thought was given to the possible use of Ga As LEDs, but it was immediately obvious that semiconductor lasers would be much better sources—if they could be developed reliably in commercial quantities. One could easily imagine an efficient Ga As laser that could couple a milliwatt of optical