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IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 3, NO. 4, AUGUST 1997 989

Introduction to the Issue on FiberAmplifiers and Lasers

OVER THE PAST DECADE, the intensive developmentof single-mode glass fiber as a powerful and versatile

gain medium has revolutionized the technology of telecom-

munications and introduced us to a new kind of laser physics.

The fiber geometry allows pump and laser radiation fields

of high intensity to be sustained over interaction lengths

of many meters with negligible propagation loss, leading to

devices that operate under extreme conditions, yet in a highly

compact and power-efficient form. The coupling between

gain and nonlinearity in these devices leads to a range of

self-adaptive behaviors that challenge both experiment and

theoretical analysis in a fascinating way. In this issue, we

sample some of the current preoccupations and achievements

in this field.The erbium-doped fiber amplifier offers performance un-

equalled by any competing device, yet must meet ever more

stringent specifications as networks grow in bandwidth and

complexity. Understanding of network behavior depends sen-

sitively on the existence of good amplifier models, which in

turn rely on a deep understanding of the physical processes at

work in the amplifier. An invited paper from Sun, Zyskind,and Srivastava expounds these relationships and introduces a

group of contributed papers which further develop the themes

of amplifier design and modeling.

The nonlinear and self-adaptive possibilities of fiber lasers

are represented here in several guises. An invited paper

by Stepanov and Cowle describes the distinctive propertiesof fiber lasers in which separate gain mechanisms, arising

from erbium doping and from stimulated brillouin scattering,

coexist. Self-mode-locking is probably the most famous type

of self-adaptive behavior in a fiber laser and a group of

contributed papers describe short pulse lasers of contrasting

types. Conversely, an invited paper by Yun, Richardson, Cul-

verhouse, and Kim describes a novel wavelength-swept fiber

laser incorporating frequency-shifted feedback, in which the

Publisher Item Identifier S 1077-260X(97)09304-0.

natural tendency of such lasers to pulse has been suppressed,leading to a narrow linewidth wavelength-scanning source.

The availability for some years now of single-mode heavy-

metal-fluoride glass fibers with low-propagation loss has lead

to extensive work aimed at exploiting the distinctive properties

of this low-phonon-energy gain medium. The weak nonra-

diative decay of dopant ion excited states that characterizes

these host glasses has allowed the demonstration of efficient

infrared-pumped visible lasing. Upconversion lasers of this

type are simple rugged devices which tolerate poor spectral

characteristics of their pump sources without loss of efficiency.

An invited paper by Paschotta, Moore, Clarkson, Tropper,

Hanna, and Maze describes the behavior of a blue thulium-

doped fluoride fiber laser under high power pumping anddiscusses the prospects for overcoming photodegredation in

these fibers to achieve stable high-power visible sources. A

further important property of fluoride fiber is transparency in

the infrared which extends to substantially longer wavelengths

than that of silica, allowing operation of laser transitions at

wavelengths beyond 2 m, of interest, for example, for gas

sensing.

We hope that these papers will convey something of the

richness and diversity of this rapidly developing field. Our

thanks are due to all the authors and reviewers whose efforts

have contributed to this issue.

ANNEC. TROPPER, Guest Editor

Optoelectronics Research Centre

Department of Physics

University of Southampton

Southampton SO17 1BJ, U.K.

STEPHENG. GRUBB, Guest EditorSDL, Inc.

San Jose, CA 95134 USA

1077260X/97$10.00 1997 IEEE

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990 IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 3, NO. 4, AUGUST 1997

Anne C. Tropper was born in London, U.K., in 1954. She was educated at the University of

Oxford obtaining a B.Sc. degree in physics in 1975 and a D.Phil. degree in 1978.

After a period of work for Smith Associates Consulting Engineers, and later as a Post-

Doctoral Research Assistant at the Clarendon Laboratory, Oxford, U.K., she was awarded a

Lindemann Fellowship to work at the IBM Laboratory in San Jose, CA, on optical dephasing

processes, with Dr. R. M. Shelby and Dr. R. M. Macfarlane. In 1983, she joined the Department

of Physics at the University of Southampton where she is now a Reader. She has been seconded

to the Optoelectronics Research Centre since its inception in 1989. Her research activities atthe University of Southampton originally included experimental studies of electron and nuclear

spin relaxation in low-dimensional semiconductor structures, and also some of the earliest

development of rare-earth-doped silica fiber lasers. Her work on doped fluorozirconate fiberlasers lead to the first demonstration of a continuously working infrared-pumped visible laser

at room temperature. Her current research interests focus on guided-wave laser sources using

novel structures and materials, and their applications in condensed matter physics.

Stephen G. Grubb received the Ph.D. degree from Cornell University, Ithaca, NY.

He is with SDL, Inc., San Jose, CA, where he works on high-power fiber amplifiers and

lasers. He formerly was with AT&T Bell Laboratories (now Lucent Technologies), Murray

Hill, NJ, where he developed high-power 1.5- m amplifiers and cascaded Raman laser and

amplifiers. He also worked at Amoco Technology Company, wher he was responsible for thefirst demonstration of the Er/Yb co-doped 1.5- m fiber amplifier.