Optics & Photonics News

Barney DeLoach (left), Richard Dixon and Robert Hartman at the ceremony for the 1993 IEEE Gold Medal for Engineering Excellence. Courtesy of R. W. Dixon

long repeaterless spans (approaching 10,000 km) now often have the high-performance lasers that encode digital information only at the land ends.

Much simpler continuously operating lasers, which carry
no signal information, are used to pump fiber amplifiers that
are periodically spaced under the sea. Data rates in a single
fiber, using very-high-speed modulation and wavelength divi-
sion multiplexing, in high-volume applications, can approach
1 Tb/s— 20,000 times higher that our initial 45 Mb/s rates!
Our program also supported what was then called “fiber-
to-the-home,” or colloquially “the last mile.” This application
took longer to become a reality because of the breakup of the
Bell System and the high costs of serving individual customers.
I was pleased, and a little nostalgic, when about five years ago
Verizon brought their laser-based FIOS product to my home.

On the consumer products side, I, at least, did not anticipate the fast and widespread application of lasers in products such as printers and CD/DVD players—or the dramatic price reductions made possible by these high-volume applications. Both the programs I worked on and their subsequent applications, through the efforts of thousands of scientists and engineers throughout the world, have succeeded beyond my wildest dreams. t

condensed-matter physics as “Schmutzphysik.” Did he mean simply that it was complex and therefore hard? Did he mean that it was difficult literally because impurities (dirt) at unheard-of small concentrations affect everything? Or did he simply mean that any elegant physics involved was hidden in an opaque matrix of mud? I sometimes thought of ourselves as the “mudders.” Fortunately, we ended up finding gold.

Bob Rediker, a professor at MIT and MIT Lincoln Labs, expressed his view of our work as follows:

I was pleased, and a little nostalgic, when about five years ago Verizon brought their laser-based FIOS product to my home.

“In the 1980s and early 1990s, I mounted
a campaign with others to insist that those
who by much hard work made inventions
practical be honored. In particular, I wanted recog-
nition for the team at Bell Telephone Laboratory.
They had increased the mean-time-to-failure at room
temperature of the double-heterostructure Ga As-
based laser … from several minutes in 1970 to an
extrapolated 8 million hours in 1978. [For this work]
B. C. DeLoach, R. W. Dixon, and R. L. Hartman
were awarded the IEEE [Gold] Medal for Engineer-
ing Excellence in 1993.”

I would like to express my gratitude to each one of the scores of professional scientists, technologists and many others who contributed to the success of the Bell Labs semiconductor laser development program during the last decades of the 20th century. It was fun being along for the ride.

Richard Dixon ( rdixon58@verizon.net) is a retired Bell Labs Technical Director, Murray Hill, N.J., U.S.A. He currently lives in Bernardsville, N.J., U.S.A.

Semiconductor lasers, then to now

Our efforts in the 1970s, 80s and 90s were aimed at Bell System applications in long-distance, high-volume voice, data and video transmission—both on land and undersea. Today, essentially all terrestrial and undersea telecommunications, data and television traffic above the local distribution level is carried in fiber using lasers as sources. The Internet would not be possible without these laser devices. Undersea cables with

ONLINE EX TRA: Visit www.osa-opn.org for a complete list of references and resources related to this article.

[ References and Resources ]

>> H. Kroemer. “A proposed class of hetero-junction injection lasers,” Proc. IEEE 51, 1782 (1963).

>> F.P. Kapron et al. “Radiation losses in glass optical waveguides,” Appl. Phys. Lett. 17, 423 (1970).

>> I. Hayashi et al. “Junction lasers which operate continuously at room temperature,” Appl. Phys. Lett. 17, 109 (1970).

>> B.C. DeLoach Jr. et al. “Degradation of CW GaAs double-hetero-junction lasers at 300K,” Proc. IEEE 61, 1042 (1973).

>> P. Petroff and R. L. Hartman. “Defect structure introduced during operation of heterojunction GaAs lasers,” Appl. Phys. Lett. 23, 469 (1973).

>> R.L. Hartman and R. W. Dixon. “Reliability of DH GaAs lasers at elevated temperatures,” Appl. Phys. Lett. 26, 239 (1975).

>> W.B. Joyce et al. “Statistical characterization of the lifetimes of continuously operated (Al,Ga)As double-heterostructure lasers,” Appl.

Phys. Lett. 28, 684 (1976).

>> R.L. Hartman, N.E. Schumaker and R. W. Dixon. “Continuously operated (Al,Ga)As double-heterostructure lasers with 70 °C lifetimes as long as two years,” J. Appl. Phys. Lett. 31, 756 (1977).