WavelengthDivision Multiplexing: Links to sites

Back to descriptions of my articles on telecommunications - especially Hybrid Fibre Coax and other broadband systems.

Robin Whittle - First Principles Consulting 29 March 1998
(Slight update to www.techguide.com URL on 17 November 1998.)

Please email me at rw@firstpr.com.au if you would like to suggest any new sites to add to this, or any corrections. In particular, if you know of any sites which are actively being maintained to cover WDM in general, then please let me know, because I am not actively searching for sites to keep this one up-to-date. Alta Vista Advanced had 2,500 hits on "wavelength division multiplexing", most of them for documents less than a year old.  The links below are far from a comprehensive survey of the field.

A hard-disk failure claimed the bookmark file with all the sites I found when I was researching the article.
For the latest updates in reverse date order, click here!

Sites linking to other WDM sites

The only such site I have found so far is:  http://www.atmdigest.com/WDM.htm This is from the ATM News Digest  http://www.atmdigest.com/ a subscription on-line newsletter service.  Watch out for the annoying Java applet with the manual typewriter sounds!
 

http://www.idot.aol.com/mld/production/yiaz1310.html

WDM sites of interest

Overviews of WDM

An excellent overview of WDM is by techguide.com : http://www.techguide.com/comm/dwave.shtml  You have to answer to the Spanish Inquisition to access this free service - but I suggest that it is well worthwhile!

Turnkey WDM suppliers

Ciena Corporation, http://www.ciena.com/ is a major supplier of turnkey WDM systems, and a current darling of the stock market.

Canadian company Cambrian Systems http://www.cambriansys.com/ specialises in WDM and photonic switching for LANs and WANs.

Fujitsu http://www.fujitsu.co.jp/hypertext/news/1997/Jan/cable.html  announces that it has been awarded the USD$84 million contract for the SEA-ME-WE 3 Cable System - section 3, of 20 Gbps initially, linking Perth, Indonesia and Singapore. Fujitsu also got the contract to build the 40 Gbps China - Japan link. Both systems are planned to be completed in January 1999.

Fibres, lasers, modulators, EDFAs and optical components

Corning is one of the biggest manufacturers of optical fibre. http://www.corningfiber.com/ Most of the site is only accessible to people who register - but this is a painless exercise.  Their SMF-LS Single Mode Dispersion-Shifted Optical Fiber - http://pro.corningfiber.com/library/pi1050.htm was until recently their state-of-the-art fibre for WDM applications.  This may now have been superseded by the "LEAF" fibre which was introduced since I wrote the article.

Uniphase Corporation manufactures laser and optical products, including Lithium Niobate optical modulators for 2.5 and 10 Gbps: http://www.uniphase.com/UTP/epd_prod.htm
 

Technical theory and reference

Suzanne Lacroix has written a detailed reference on fibre-optic theory:   http://opt-fibres.phys.polymtl.ca/Fibers_html/node1.html

Monash University Associate Professor Jim Breen, at http://www.dgs.monash.edu.au/~jwb/subjects/dgs6910/  provides some excellent reference material on "Fibre Optics in communications, including photonic switching", including material on fibre manufacture and laser diodes.  His site also contains material on telecommunications from the historical technologies, to the very latest

OKI has a glossary of fibre and laser terminology: http://www.okisemi.com/public/nf/LaserGlossary.html

The Information Superhighway Provides an On-Ramp for the Underwater Industry An interesting and detailed article by Howie Doyle in UnderWater Magazine, on the laying of submarine cables.  http://www.diveweb.com/uw/uwarch/uw-su97.02.htm
 

Research

Lightwave Xtra http://www.light-wave.com/ is the "online companion to Lightwave, the monthly publication of choice for news and information about fiber-optic communications technology and applications worldwide."  Looking beyond current approaches to WDM, is an article http://www.broadband-guide.com/lw/feat/feat2983.htmlSolitons Form Basis for WDM Replacement Technology by Eric J. Lerner. Solitons are single pulses of light, which can be made to propagate and be amplified for very long distances without dispersion.  This is achieved by the light itself altering the properties of its waveguide (in this case the refractive index of the fibre) so that it remains gathered together as a single pulse, and is not dispersed.

There are at least two research teams fabricating infra-red laser diodes which are infinitely tunable (over a certain range) by application of an electrical voltage - which creates an electrostatic field, which moves a mirror, which changes the resonant wavelength of the lasing cavity.  Stanford researcher Fred Sugihwo http://www-snow.stanford.edu/~fred/ is on one of the teams researching Micromachined Tunable Vertical-Cavity Surface-Emitting Lasers
(Mi-T-VCSELs).  See diagrams, electron microscope images and performance graphs here and here. Hai-Sheng Wang at Cornell is working in the same field, but there does not seem to much on the Net about this project, except this.

Jocelyn Nee has photomicrographs of Surface-Micromachined Diffraction Gratings: http://ilpsoft.eecs.berkeley.edu:9636/~ilpsoft/98abstracts/jnee.1.html This includes a picture of a planar silicon diffraction grating hinged on a silicon substrate so its angle of incidence to the light can be altered (in some way that is not clear to me) electrically.
 

Standards

Paul A. Bonenfant's article on ITU standardisation efforts in optical communications is at:    http://www.broadband-guide.com/lw/standards/stand1197.html

Real and potential long-haul WDM projects

Project Oxygen http://www.oxygen.org/ is by far the most ambitious plan for fibre-optic communications.  It depends on WDM, and is yet to recieve the support of the major telcos.  Their plans for un-repeatered links based on eight 10 Gbps channels of WDM per fibre (with optical amplifers, but no opto-electrical-opto regeneration) across the Pacific (New Zealand to Chile) seem to be beyond the current technology, due at least to polarisation mode dispersion, and quite likely other limitations, especially signal-to-noise ratio after several dozen EDFAs.  Details: http://www.oxygen.org/pre013.html, http://www.oxygen.org/pre014.html,    Lets hope they figure out how to do it!  Their cables are planned to form a network all over the Earth.  The undersea cables are 320 Gbps: 4 fibre pairs of 80 Gbps each, and the land links 960 Gbps with 12 fibre pairs.  There map at http://www.oxygen.org/oxygen_worldmap.html and the various network loop diagrams indicates that Australia would be connected to the outside world by four 320 Gbps redundant loops, the Oceania , West Australian , East Australian and South Indian Ocean loops.  Now . . . that's 1,280 Giga bits per second. Currently, apart from the recently activated Jasuraus cable, Australia has about 1.5 Gbps of fibre connectivity to the outside world.  Say there are 20 million people in Australia (currently 18 or 19 million?) that is 64,000 bits per second per person in Australia, which is cute - 64kbps is the data rate of a normal telephone call.  Now, consider this in terms of digital audio, which is 1.4112 Mbps for CD format 16 bit 44.1 kHz stereo . . . that is 907,000 Australians listening to perfect quality digital audio from overseas - or more to the point exporting music to those not lucky enough to be here!  See my paper on Music Marketing in the Age of Electronic Delivery at http://www.ozemail.com.au/~firstpr/musicmar/  Digital Audio can be compressed losslessly to about 60 to 80% of its original size - so we need some serious bandwidth to be able to deliver an hour of music (635 Megabytes without compression) to customers anywhere in the world for a few dollars.
 
 

This is not complete yet.  I have more searching to do!  Please check back in early April.

Hard-copy articles

These are articles from printed journals - which are not, as far as I am aware, available on the Net.

Two articles from the SubOptic 97" conference in San Francisco in late 1997 - a four yearly conference on submarine cable systems.  Reliable sources have told me that SubOptic '97 conference proceedings are available from David R Sprawls, Deputy Director of Tyco Submarine Systems Ltd (formerly AT&T SSI) on fax +1 973 326 2609.  Either paper (bound) or CD format are available.
 
 

WDM System Design Principles of Repeatered Undersea Fiber Optic Networks S.M. Abbot, W. C. Marra and J. Schesser  AT&T Submarine Systems Inc.  Proceedings of the Sub Optic Conference in San Francisco. (See note above.)   Pages 521 to 529. Detailed overview of all the issues in designing undersea WDM systems, including such things as exact allowances for all the forms of loss and gain in the system.  I received a copy of this article and the next from Telstra after I nearly completed my article. Probably the best single article on this subject.

Fiber-Based Optical Components for Submarine Systems  A. Wada, K, Shima, H Sasaki, R Mtsumoto, N. Tanaka, F. Suzuki and R. Yamauchi.  Fujikura Ltd. Proceedings of the Sub Optic Conference in San Francisco. (See note above.) Pages 688 to 690.  Discussion of finer points of couplers and Fibre Bragg Gratings, such as polarisation and temperature stability.
 
 

Fiber Bragg Grating Technology Fundamentals and Overview. Kenneth O. Hill and Gerald Meltz.  Journal of Lightwave Technology, Vol. 15, No 8, August 1997  Pages 1263 to 1275.  An excellent overview of this delicate and important technology.  This journal is carried by the RMIT University central library in Melbourne.

Fiber Bragg Gratings for Dispersion Compensation in Transmission: Theoretical Model and Design Criteria for Nearly Ideal Pulse Recompression  Natalia M. Litchenitser, Benjamin J. Eggleton and David B. Patterson. Journal of Lightwave Technology, Vol. 15, No 8, August 1997  Pages 1303 to 1313.  Deep material on designing FBGs which compensate for the differing propagation speeds of differing wavelengths in the hundred or so kilometres of fibre which precedes it.  "Apodised" is another term for what is called "windowing" in Digital Signal Processing - it is a way of shaping the overall envelope of the impulse response of the filter to achieve the best tradeoff between pass-band performance and the response at other frequencies which the designer wishes to ignore.
 
 
 

Updates sorted by date

• 17 November 1998 Slight update to www.techguide.com URL.  Other projects have overtaken this one - so I don't plan to add more links.
• 29 March 1998 New file, but incomplete so far - more searching to do!.

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