“For their outstanding contributions to telecommunications through the invention and development of the erbium-doped fibre amplifier (EDFA) which enabled the global high-capacity optical fibre network.”

INVENTORS OF THE ERBIUM-DOPED FIBER AMPLIFIER

There are times, when a technology takes a giant leap forward. In optical telecommunications this happened between the mid-1980s and 1990s when a device called the erbium-doped fibre amplifier was born, grew up and went to work. It revolutionized telecommunications and is nowadays a vital part of the global optical fibre network that is the backbone of the information age. Our entire modern way of life - from business to pleasure, education to entertainment and security to human rights advancement - is dependent on the optical fibre network.

Dr. Emmanuel Desurvire, Dr. Randy Giles and Prof. David Payne are the men behind the erbium-doped fibre amplifier. Desurvire and Giles were working together at the famous Bell Laboratories in New Jersey, USA, and Payne was at Southampton University. These two groups were competitors, but spurred each other on, benefiting from each other’s work. Prof Payne was first to publish a paper about erbium-doped fibre amplifiers, but Dr Desurvire and Dr Giles were first to make it a working tool.

There had long been a recognized need for some kind of optical amplifier. Before its invention, the laser signal in the fibre cable was boosted electronically by receiving the signal, transforming it into an electronic form and resending it ahead with a new laser. This was power consuming and impractical and restricted the use of fibres since one fibre can carry many laser signals of different wavelength and polarization, but an electronic amplifier can only handle one laser signal at a time. A long distance connection needed these amplifiers every 500–600 km because of the attenuation of the fibre.

Aggressive work was being done on semiconductor optical amplifiers, but because of the constraints of the electronic amplification, there was a need for an optical amplifier. One had been made in the 1960s by Dr. Elias Snitzer of The State University of New Jersey who placed erbium in fibre and used different means to excite them to produce gain. At that time he did not have the required lasers and his group used flashlights to produce light. The signal’s duration was only milliseconds and without the appropriate lasers, the research reached a dead end.

Twenty years later lasers were widely available and many groups around the world were working on the optical amplifier. They were exploring different ingredients that could be added into fibre to extract more gain. In mid 1990, significant work was done specifically on erbium at Southampton University and AT&T Bell Labs. Bell Labs had made the first fibre laser pumped with a laser diode source as far back as 1974 and it had continued the research. In Southampton, Professor Payne’s research group had started reexamining rare-earth doped fibres in 1985 and a year later they had their first encouraging results when they managed to run a room-temperature erbium fibre laser at 1.5 µm. Soon after they made the first erbium fibre laser amplifier: a bit of fibre with some erbium on it, a laser source and couple of optical isolators that prevented the feedback from the amplified light.

At the same time Dr Desurvire started to investigate erbium-doped fibre amplifiers at Bell Labs. Both Bell Labs and Professor Payne’s lab in Southampton spent the next few years testing known materials and searching the new materials for doping the optical fibre. Attention shifted to practical issues such as how optimum performance could be achieved; how much erbium should be in the fibre and what the optimum length of fibre should be.

While the basics were well understood, there was still a practical problem: the big and bulgy argon lasers that the laboratories used had to be replaced with smaller semiconductor laser diodes, but there were no diodes powerful enough, at the desired wavelength. In 1989 the Japanese company NTT came up with a high-gain laser diode that produced suitable 1.48 µm wavelength light. Bell Labs secured the right to acquire the diodes and soon after, made the first practical erbium-doped fibre amplifiers.


Principle of the optical fiber amplifier

The principle of the optical fibre amplifier is quite simple: take some optical fibre with some optically special material inside and, using a laser, target some light into it. The optical amplifier can also be considered as a laser without feedback. So whereas the laser’s purpose is to generate coherent light; the amplifier boosts that light.

Physically, amplifiers are just a laser source (a laser diode or array of laser diodes) and can be regarded as specially doped optical fibre, reeled in coil with optical isolators and filters needed for shepherding the light. For scientists the challenge was threefold: finding the doping material, putting it inside the fibre and making a suitable pumping laser.

The basic idea of amplification had been known for a long time. If you target a laser in ions, the ions alter their energy level from lower to higher. They can drop back to a lower energy level only after they have emitted the extra energy by sending out a photon that corresponds with the difference in energy levels. When the energy levels are right, the extra photons emitted by the ions are at the same wavelength as the light that needs to be amplified, and thus the exit signal is more powerful than the entering signal. The signal has been amplified by the stimulated emission of photons from dopant ions in the doped fibre: it has stolen some energy from the pump laser.

Erbium (Er) is a chemical element with atomic number 68, making it one of the heaviest elements of the periodic table before the radioactive metals. This rare earth metal was discovered by Carl Gustaf Mosander in 1843 in Ytterby, Sweden. Its salts are rose-colored, and the element has characteristic sharp absorption spectra bands in visible light, ultraviolet, and near infrared - and it is optically very interesting.

When the core of a silica fibre is doped with trivalent Erbium ions (Er+3) and is efficiently pumped with a laser at 980 nm or at 1,480 nm, it exhibits gain in the 1,550 nm region. Erbium was perfect for silica-based optical fibre communications, because the standard single mode optical fibres have minimal loss at 1525 nm – 1565 nm wavelength. Erbium works fine also with other widely-used transmission window at approximately 1570 nm to 1610 nm.

The most recent version of the optical amplifier is the Raman amplifier, where the coil of erbium-doped fibre can be much shorter than in the traditional Erbium amplifier. The pump power required for Raman amplification is higher than that required by the traditional Erbium amplifiers, with in excess of 500 mW or even over 1W of optical power. The principal advantage of Raman amplification is its ability to provide distributed amplification within the transmission fibre, thereby increasing the length of spans between amplifier and regeneration sites.


Applications

The first commercial use of erbium-doped fibre amplifiers was in underwater communication cables, where the advantages of the optical amplification of the laser signal are considerable. The amplifiers are inside torpedo-like repeaters that are placed in cable between 500 - 800 km. Modern systems also permit wavelength-division and polarization multiplexing, which dramatically increases the capacity of the fibre.

Communications satellites lost most of their North Atlantic telephone traffic to these low cost, high capacity cables. The depression that hit the communication satellite markets and commercial launcher business in 1990s was largely due to the introduction of the erbium-doped fibre amplifier and the huge increase in cable bandwidth it made possible.

Nowadays the optical amplifiers are widely used in all kinds of optical networks - terrestrial and underwater. Their importance is increasing as the optical cables gradually replace older copper cables and domestic use expands. The smallest amplifiers are the size of match box while the underwater repeaters are several meters long.

Optical amplifiers are used also in industries where high power lasers are used for cutting, marking and machining. Surgical lasers also make wide use of the amplifiers.

Optical amplifiers are now produced all over the world, but there are just a couple of companies manufacturing erbium-doped optical fibre. Southampton Photonics (SPI), co-founded by Professor Payne, is one of the manufacturers of this fibre and it is a leading company in the manufacture of industrial and surgical lasers.

Potential applications in the future

The most obvious future use of optical amplifiers lies in the exponential demand for high speed internet connectivity and the booming need for greater communications capacity.

Industrial applications are also increasing steadily as the power of the laser beams available increases. The laser can be used in heavy industry, but also it enables many smaller businesses with highly personalized services and allows economic production of a small series or special order of products.

There will be a need for new kinds of optical amplifiers when the quantum computers and optical systems will come.


Further reading

http: //en.wikipedia.org/wiki/Optical_amplifier
http: //en.wikipedia.org/wiki/Optical_fibre
http: //www.alcatel-lucent.com/bell-labs
http: //www1.alcatel-lucent.com/submarine/
http: //www.thalesgroup.com/
http: //en.wikipedia.org/wiki/David_Payne
http: //www.orc.soton.ac.uk/


Emmanuel Desurvire: Erbium-Doped Fiber Amplifiers, Principles and Applications (ISBN-13: 978-0471264347); Wiley-Interscience; New Ed edition (August 19, 2002)

Emmanuel Desurvire: Erbium-Doped Fiber Amplifiers, Device and System Developments (ISBN-13: 978-0471419037); Wiley-Interscience; Subsequent edition (August 8, 2002)


CV - Professor Emmanuel DESURVIRE

French Citizen
Born 1955 in Boulogne, near Paris, France
Married

1974 Baccalauréat, Lycée Claude Bernard, Paris
1977 B.S. in Physics, Paris VI University
1980 M.S. in Physics, Paris VI University
1981 M.S. (DEA) in Theoretical Physics, Paris VI University
1981 - 1983 Ph.D. Student, Thomson-CSF (now Thales) Central Research Facility Corbeville, Orsay, France
1983 Ph.D. in Applied Physics, University of Nice
1984 - 1986 Postdoctoral Research Affiliate, Applied Physics Department, E. L. Ginzton Laboratory, Stanford University, USA
1986 - 1990 Member of Tecnical Staff, AT&T Bell Laboratories, Crawford Hill Laboratory, New Jersey, USA
1998 Sc.D. (HDR Thesis), University of Nice
1990 - 1993 Associate Professor, EE Department of Columbia University, New York, USA
1994 - 1998 Group Leader, Undersea Transmission, Alcatel-Alsthom (later Alcatel-CIT) Research, Marcoussis, France
1998 - 1999 Deputy Unit Director, Photonics Networks Unit, Alcatel-CIT, Marcoussis, France
1999 - 2000 R&D Project Manager

Notable prizes and awards

1992-93 Distinguished Lecturer Award, Lasers and Electro-Optics Society (IEEE)
1984 International Prize In Optics , International Commission for Optics (ICO)
1998 Benjamin Franklin Medal In Engineering, Benjamin Franklin Institute
1998 Grand Prize in Electronics of Gai A.Ferrée, Federation des Anciens des
Transmissions
2000 IEEE Fellow, Institute of Electrical and Electronics Engineers (IEEE)
2001 Distinguished member of Technical Staff, Alcatel Technical Academy
2004 Alcatel Fellow, Alcatel Technical Academy
2005 William Strelfer Scientific Achievement Award, Lasers and Electro-Optics Society (IEEE/LEOS)
2006 Thomson Scientific Laureate, Thomson Scientific
2007 John Tyndall Award, Optical Society of America and Lasers & Electro-Optics Society
(OSA/LEOS)
2007 Prix France-Telecom, France's Academy of Sciences

Patents and publications

210 publications (98 Journal, 104 conference, 8 book chapters)
5 author books (publications 1994,2003,2004 and 2008)
113 patents in 34 patent families


CV - Dr. Randy GILES

Citizen of the USA and Canada
Married with two children

1976 BSc in Physics, University of Victoria, Canada
1978 MSc in Physics, University of Victoria, Canada, 1978
1983 PhD in Electrical Engineering, University of Alberta, Canada
1983 - 1986 Member of Scientific Staff at Bell Northern Research in Ottawa, Canada
1986 - 1999 Member of Technical Staff at Bell Laboratories
1999 - 2001 Technical Manager at Bell Laboratories
2000 - Director, Optical Networks at Bell Laboratories
2001 Director of Photonic Subsystems Research at Bell Laboratories
2001 - 2006 Director of Advanced Photonics Research at Bell Laboratories

Notable prizes and awards

2000 Awarded the Discover Magazine Technology Award
2000 Awarded Fellow status In the Optical Society of America
2001 Awarded the Bell Laboratories President's Gold Award
2001 Awarded the Bell Laboratories Fellow
2005 Awarded the Fraunhofer Award/Burley Prize from the Optical Society of America

Patents and publications

Authored or co-authored over 100 publications/conference papers.
Have over 50 patents filed and more than 30 issued.


CV - Professor David PAYNE

British Citizen
Born 13 August 1944
Married


1949-1963 Primary and Secondary Education in Central Africa (Zambia)
1964-1967 B.Sc. Honours, Electrical Engineering, University of Southampton, UK
1967-1968 Diploma in Quantum Electronics, University of Southampton, UK
1969-1976 PhD degree, University of Southampton, UK (Part time Registration)
1969-1971 Research Assistant, Dept. of Electronics, University of Southampton
1971-1972 Junior Research Fellow, Dept. of Electronics, University of Southampton
1972 Pirelli Research Fellow, University of Southampton, UK
1974 Optical Communications Group Leader, University of Southampton
1978 Senior Research Fellow, University of Southampton, UK
1981 Principal Research Fellow, University of Southampton, UK
1984 Reader, University of Southampton, UK
1989 Deputy Director, Optoelectronics Research Centre, University of
Southampton, UK
1991 Professor of Photonics, University of Southampton, UK
1995 - Director, Optoelectronics Research Centre, University of Southampton, UK

Commercial activity

1981 - 1991 Co-founder and Director, York Technology Ltd. (now PK Technology Inc.), UK
1991 - 2000 Founding Consultant, Sensor Dynamics, UK (now part of SENSA)
1987 - 1990 Consultant, Amoco Technology, Naperville, USA
1995 - 2000 Consultant, Scientific Atlanta (ATx), Naperville, USA
1998 - Co-founder, Director and Chairman, Southampton Photonics Inc.
1999 - 2001 Director, Geosensor, USA

Notable prizes and awards

1982 Academic Enterprise Award for establishing York Technology
1986 Queens Award for Industry (York Technology)
1991 IEEE/OSA John Tyndall Award (USA)
1991 Rank Prize for Optics (UK)
1992 Elected Fellow of the Royal Society
1993 Computers and Communications Award (Japan)
1994 MASTS (USA) Real Advances in Materials Award
1896 Elected Fellow of the Optical Society of America
1997 One of 12 scientists included in the Optical Society of America's time capsule due to
be opened in 2016
1998 Benjamin Franklin Medal in Engineering-Franklin Institute USA
1998 Elected to the Royal Society of Arts
2000 ISI Certificate for one of the world's most cited authors
2001 2001 Basic Research Award of the Eduard Rhein Foundation
2001 Ernst and Young Entrepreneur of the Year finalist
2001 Mountbatten Medal of the IEE for outstanding contributions to electronics
2002 ISI Certificate for Highly Cited Researchers - original member
2003 LEOS (USA) Distinguished Speaker
2003 IEE Distinguished Speaker
2004 Appointed Commander of the British Empire (CBE)
2004 Elected to the Norwegian Academy of Sciences
2004 Kelvin Medal of the 8 major UK engineering institutions
2005 Elected Fellow of the IEE
2005 Elected Fellow of the Royal Academy of Engineering
2005 Royal Academy of Engineering MacRobert Award finalist (SPI Lasers)
2007 Elected to the Russian Academy of Sciences
2007 IEEE Photonics Award for outstanding achievements in photonics

Patents and publications

Author and co-author of over 600 Journal and Conference publications. Inventor and co-inventor on over 20 Patents and Applications

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