Talk:Optical fiber

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Good article Optical fiber has been listed as one of the Engineering and technology good articles under the good article criteria. If you can improve it further, please do. If it no longer meets these criteria, you can delist it, or ask for a reassessment.
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To-do list for Optical fiber: edit · history · watch · refresh
  • Expert peer review for the areas on long-distance (telecom) links.
  • In the history section, add contributions of NTT.
  • In the history section, mention the introduction of EDFAs into real-world service (date and details).
  • Use suggestions from Peer Review.
  • Explain why, if it's glass, it doesn't break.
WP:TEL This article is within the scope of WikiProject Telecommunications, an attempt to build a comprehensive and detailed guide to telecommunications on Wikipedia. If you would like to participate, you can edit the article attached to this page, or visit the project page, where you can join the project as a "full time member" and/or contribute to the discussion.

Contents

[edit] Photonic crystal fibres

Should there be a mention (or link) of photonic crystal fibers somewhere in the article. This seems to me to be a major (and interesting) development in the field of optical fibres, with an entirely new method of guiding light (for example light can be guided in air, with less loss etc) User:DMB 14:33, 5 January 2006 (UTC)

Yes, it would be very appropriate to mention them somewhere in the article. I added a link in the "see also" section, but this is probably not sufficient.--Srleffler 02:28, 6 January 2006 (UTC)
added to the history section - could someone please clean up the citations, as I cannot do it! Also, please feel free to edit with more appropriate information.
Agreed this is an important area of current research, and beginning to be commercialized, but I'm generally somewhat sceptical of anything with the level of hype surrounding it as photonic crystals. I've tried keep the important information in what you wrote, while removing some of the NPOV phrases. For example, I removed "entirely new" because as pointed out in the photonic crystal article, these structures have existed in nature forever. I also replaced "many advantages" with two examples of specific advantages. -- The Photon 06:06, 7 January 2006 (UTC)
OK, maybe I should have said "entirely different" rather than "entirely new", but the current revision seems good to me. DMB 16:06, 7 January 2006 (UTC)

[edit] electrical resistance

In the section "Comparison with electrical transmission", the article mentiones High electrical resistance for fiber optic cables. I'm wondering whether this means higher electrical resistance than electric cables, or complete electrical resistance instead. Would be nice if someone cleared that up.

  • Well, electical resistance is never "complete" - it's always some finite value, even if it's really high. In general, the electical resistance of glass fibre is as high as any other piece of glass, i.e. pretty damn high. --Bob Mellish 15:27, 17 November 2005 (UTC)
    • Stupid me.. I mixed up with "Immunity to electromagnetic interference", which is printed just above it!!! Thanks anyway  :)

[edit] Corning

I was surprised to see Corning refered to as a British company. Unless there is something very subtle (like their distant origins), Corning is surely american - based in Corning, NY. Keck and co-workers, I am certain, did their pioneering work in the USA.

There are at least three different histories of the development of optical fibre - British, Japanese and American. The British credits Kao and Hockham and the Post Office Research Centre, The Japanese credits Nakahara and Sumitomo, the American credits Keck and Corning. That's a very simplistic summary, but the essence is correct - it depends mostly on the nationality of the author / teller of the history. My view? It was an idea whose time had come and all parties were innovating at the same time and contributed to the progress. —The preceding unsigned comment was added by 138.130.64.75 (talk • contribs) .

Actually, they each made complimentary contributions to the art. The BPO, known then, establihed the requirements through the Kao Hockman papers. Corning invented a viable process and material for making fiber. Other companies in Japan and elsewhere created many needed components for fiber systems. Numerous patent trials through the 1980's established the primacy of Corning's (a NY company) inventions, on a world wide basis. This is not to discredit the contributions of others in many very important areas. The case is clearly laid out in "The Silent War" Magaziner 1990. —The preceding unsigned comment was added by 66.24.214.136 (talk • contribs) .
Corning's roots are very American -- it was founded in the 19th century in Corning, New York where it is still headquartered; the company was named after the town. Today, the company is very global and I would not be surprised if they have as many, if not, more employees overseas as in the U.S. --A. B. 17:31, 13 October 2006 (UTC)

[edit] Inconsistency in range

Which is correct? The article states "Typical single mode fibre optic cables can sustain transmission distances of 80 to 140 km" but then "Recent advances in fiber technology have reduced losses so far that no amplification of the optical signal is needed over distances of hundreds of kilometers". One or the other is the state of the art... which is it!!!! I need to know!

>> "Recent Advances" vs. "Typical Fiber". ;)

[edit] optical waveguide cables

While editing another wikipedia article (translated from German/Deutsch, if that makes any difference), I see the term "optical waveguide cables". Is that exactly the same thing as "optical fiber", or something different ? Is this phrase common enough to mention in the article ? --DavidCary 21:44, 17 May 2005 (UTC)

Yes the optical fiber is used as a waveguide purpose, you see for any communication purpose we require a communication channel, and the term optical waveguide cable means this communication channel.--Mascotmayank (talk) 05:58, 12 June 2008 (UTC)

[edit] Fiber vs Fibre

Is there a reason why fibre is used instead of fiber 4 times in the article? The only mention I see is at the beginning, where it states that fibre is the British term. I can't see any contextual differences between the use of fiber and fibre, and unless someone has a reason, will change all instances to fiber.


>1. It helps with search engines >2. Brits and Aussies editing the page will use fibre, while USA uses fiber.

While I certainly want people to come read this page, whether they type "fibre" or "fiber" into their search engines, it just seems inconsistent for the article title to say "fiber" while the article text uses "fibre". --DavidCary 21:44, 17 May 2005 (UTC)

Please see Wikipedia:Manual of Style#National varieties of english. The guideline is for each article to be internally consistent. I have made all the uses of fibre consistent with the article title (fiber). The main gotcha would be if the Fibre Channel standard should be mentioned, the title of that standard uses the British spelling. To aid the search engines, there should be a "redirect page" from "Optical Fibre" to this page. If it's not there, I will figure out how to create it.--The Photon 16:18, 12 October 2005 (UTC)

Any reason why there's a 'See also Muggle' under the prospects for the future of fiber optic technologies? Seems to me some kid playing a prank. . .

[edit] Optical fiber in waveguides

“Optical fiber in waveguides” piece probably refers to some advanced integrated optics application, or some optical backplane application. However in present form is uninformative and misleading. Could somebody please correct this paragraph. Or, may be, we should remove it. --Sergiusz 23:27, 3 Jun 2005 (UTC)

I support removing the sectionThe Photon 05:01, 12 October 2005 (UTC)
Unless its meant to be a reference to something like [1], in which case, somebody please write it up so it makes sense.--The Photon 04:49, 23 October 2005 (UTC)

I am removing this section from the main article. Here is the old text in case someone would like to recreate it (--The Photon 05:05, 28 October 2005 (UTC)):

Optical fiber in waveguides Waveguides are silicon chips with extremely thin and extremely flexed optical fibers on them. Companies like JDS Uniphase manufacture these waveguides for use in computers and in splitting boxes. A waveguide separates the different colors of light, and allows it to have the same signal sent in many directions. (see waveguides)

[edit] Britishisms

While I fully support alternate spellings, isn't claiming the Corning corporation a bit much?

[edit] Tb/s

"Large data-carrying capacity (thousands of times greater, reaching speeds of up to 1.6 Tb/s in field deployed systems and up to 10 Tb/s in lab systems)" these are Terabits or Terabytes?

Ans: Terabits

[edit] To be included, FO Transmission Records

RELEASE FRIDAY MARCH 22, 2002. Bell Labs scientists transmit 64 channels of data at 40 gigabits per second per channel (2.56 Tbps) over 4000 kilometers (2500 miles)

In OFC 2005 paper by a group from Agere Systems -- a record-setting fiber optic transmission rate of 3.2 Tbps. --Sergiusz 20:49, 16 September 2005 (UTC)

[edit] Added Manufacturing

Hello,

I added manufacturing by MCVD, but was unsure how to reference the article. Can someone please have a look at this? Thanks.

You did fine! One thing you might want to do now is to find those terms in your new text that reference other Wikipedia articles, and make them Wikilinks by enclosing the term in square brackets like so: [[Chemical vapor deposition]]. You can also reference an article using a different term than the actual article name, like so: [[Chemical vapor deposition|Modified Chemical Vapor Deposition]]; the first part is the actual article title and the second part is what will show up here in the article, for example: Modified Chemical Vapor Deposition.
Remember, though, Wiki standard practice is to only make a term a Wikilink the first time that it appears in the article. Subsequent reuses of the term aren't Wikilinked.
Also, you may want to "sign" your talk postings (here) by putting four tildes (~~~~) after your post. When you press "Save page", these will be replaced by your username or IP address in a handy Wikilinked format. A timestamp will also be included.
Atlant 13:54, 3 October 2005 (UTC)

[edit] Removed text on Svetlana Plant, Saint Petersburg

I removed this text:

Svetlana plant in Saint Petersburg, Russia was first who decided to use fiberoptics in house aronments and decorations. Namely in Fiberoptic UFO lamp, which look like this. [url]http://www.thingsthatglow.com/html/images/8612.jpg[/url]

The lamp from light travels through painted glass, then through fiberoptics.

Reason: Hecht mentions decorative lamps of this type around 1958, but gives no solid citation.

If there's any citation for these lamps at an earlier date in St Petersburg, please re-add the text with citation. If the St Petersburg lamp doesn't predate 1958, but if the image is available under a free license, consider using it to illustrate the "Other uses of Fiber Optics" section.

--The Photon 00:07, 30 October 2005 (UTC)


[edit] Plastic

This article mentions plastic optical fiber a couple times, but the rest of the article is glass-centric (don't worry, no NPOV here... <g>). POF and it's uses should be added as a new section, and the rest of the sections called glass-specific.

Unfortunately, I don't know much about POF.

XPav 03:52, 14 December 2005 (UTC)

Plastic optical fiber has its own article, but it wouldn't be a bad idea to summarize it here, in Wikipedia:Summary style. In relation to what's here, POF is multimode step-index fiber, with relatively high attenuation (~1 dB/m). The applications I know about are mostly in audio electronics.
The Photon 04:44, 14 December 2005 (UTC)

[edit] Is this the same Peter Schultz?

Is this Peter Schultz the same one referenced in the "History" section of this article?

Based on the biography at shultz.scripps.edu, I'd say say "No." -- The Photon 05:17, 4 January 2006 (UTC)

[edit] Put the history first.....

Hi..

i would like to see the history section be after the principle..... it doesn't make sense putting it at the end..... Jayant, 17 Years, India|(Talk) 05:30, 24 February 2006 (UTC)

For articles on technical and scientific topics, the history is often not all that important compared to the technical details and applications.--Srleffler 06:58, 24 February 2006 (UTC)

[edit] Fiber optic cable

I think the whole area of fiber optic cable should either be expanded or else moved to a separate article with a summary and link here. Your thoughts?--A. B. 01:19, 2 June 2006 (UTC)

No need to ask -- be bold and expand the section. If it gets too out of balance with the rest of this article, that's the time to split it out to its own article. -- The Photon 01:36, 2 June 2006 (UTC)

[edit] Wavelengths in vacuum or in fiber ?

"The fiber absorption is minimal for 1550 nm light and dispersion is minimal at 1310 nm making these the optimal wavelength regions for data transmission. A local minimum of absorption is found near 850 nm..." Are these wavelengths of light in vacuum or in fiber ? 83.17.206.178 16:10, 10 June 2006 (UTC)

Glass (i.e., fiber).
P.S. Welcome to Wikipedia -- I encourage you to get your own user name; the IP address you originally edited from appears to be a shared IP address and has been used by someone for vandalism. As a result, you could encounter hassles editing Wikipedia. An account takes just a minute or two to set up and makes you and your contributions independent of the ISP you use. See Wikipedia:Tutorial (Registration)--A. B. 16:12, 10 June 2006 (UTC)
I don't think you're right, A. B. I'm pretty sure these are vacuum/air wavelengths. If you are right, I spent four years developing a telecomm laser for the wrong wavelength. --Srleffler 16:35, 10 June 2006 (UTC)
You're right; I stand corrected:
  • pp 418-420, Hecht, Jeff, Understanding Fiber Optics, 4th ed., Prentice-Hall, Upper Saddle River, NJ, USA 2002 (ISBN 0130278289)
  • pp 252-253, Ramaswami, R., Sivarajan, K. N., Optical Networks: A Practical Perspective, Morgan Kaufmann Publishers, San Francisco, 1998 (ISBN 1558604456)

[edit] speed of transmission

The light travels at 2/3 the speed of light in a vacuum. How fast does an electromagnetic wave travel in a copper wire system like 10baseT? Does the fact that the light bounces off the walls at an angle mean that light has to travel further than the straight line length of the fiber? --Gbleem 19:42, 26 June 2006 (UTC)

Copper and fibre have roughly-similar propagation velocities.
The path length on a multi-mode optical fiber definitely does vary depending on the angle that any given ray launches into the fibre at. For single-mode optical fiber, everything tends to propagate basically straight, which is why you can go a much longer distance in such a fibre without your pulses "smearing" out into mush.
Atlant 20:26, 26 June 2006 (UTC)

[edit] Fiber-end polishing styles?

One web site offers angled, flat or conical polishing. Why would I want one or the other. --Gbleem 20:52, 26 June 2006 (UTC)

Angled polish is used on singlemode fiber to get very low backreflection. The angle causes any backreflected light to leak out of the fiber, so it does not go back down the fiber to the originating equipment.
There is a lot more to be said about fiber polishes, but I don't have time right now.--Srleffler 23:22, 26 June 2006 (UTC)

Some common fiber polishes:

  • flat: might be used for multimode fiber, or for coupling from fiber to free space optics, or for splicing (I'm not sure)
  • physical contact (PC): Used for mating singlemode fiber. The surface is slightly curved, so that the fibers touch only at their cores. Some manufacturers might call this "flat", in contrast to APC (below).
  • angled physical contact (APC): Same as PC, but the slightly-curved surface is tilted (8°, I think) from perpendicular to the fiber axis. This increases loss, but decreases backreflection. APC fiber ends must only be mated to other APC fiber ends. The strain relief on an APC connector should always be green to indicate this. Jacks on instruments are not always marked.
  • angled flat: a flat polish, tilted (at 8°, I think). This is used for coupling from fiber to free-space optics, with low backreflection. This polish is fairly rare.

There are several grades of PC polish, typically identified by manufacuters as regular, "super" and "ultra". The higher grades provide lower insertion loss and backreflection, typically at higher cost. The latter two are sometimes identified as SPC and UPC polish. All of the PC polishes except APC are compatible with one another.

I'm not sure what the conical polish is. It may be for some special purpose.--Srleffler 04:03, 4 July 2006 (UTC)

Conical polish approximates a lens at the output, focussing the output beam. I'm not sure if this is ever used outside research labs. -- The Photon 02:37, 16 July 2006 (UTC)

[edit] Uses of Optical fibre as a replacement of traditional "copper" lines for the transfer of data

This is a very useful article, but I am missing some additional input from experts out there (there is bound to be somebody) on the use of optical fibre instead of copper fibre. Any takers?—The preceding unsigned comment was added by 81.169.127.6 (talk • contribs) .

See article on FTTP for practical application of PON technology to replace existing copper wire with fiber optic plant, and Verizon's FiOS roll out using BPON technology. This is a very broad subject, if there is anything you are specifically curious about, I'll be happy to discuss. --Toddyboy711 19:19, 16 May 2007 (UTC)

[edit] Principle of operation

I re-reorganized the Principle of operation section. The article needs to start with a section that focuses on how an optical fiber works, rather than focusing on cataloguing types of fiber. We can do both, but not the way the previous reorganization structured it. In particular, that edit implied that one can divide fiber into four distinct types: step index, graded index, multimode, and singlemode. That's misleading. Multimode and singlemode fiber can each be either step index or graded index (although graded index singlemode fiber is not used commercially as far as I know). I think it flows better to divide into single- and multimode, and deal with step vs. graded within the sections. That allows us to focus on how fiber works, without totally rewriting the section.--Srleffler 04:08, 19 September 2006 (UTC)

[edit] Fragility and disaster preparedness?

The article doesn't mention how fragile the lines are compared to copper wires. What kind of estimates are there for this service in emergencies? —The preceding unsigned comment was added by 71.103.84.158 (talk • contribs) .

Actually, fiber optic lines are probably more likely to survive many disasters. For example, pure fiber optic lines are essentially immune to EMP, lightning, and other electrical disturbances. (The same can't be said, unfortunately, of fiber optic lines that contain electrical repeaters, though.) Fiber cables are also quite likely to be more immune to prompt failures from fire.
If you're thinking that glass is fragile, this really isn't so. The fiber is usually quite loose within a toughened over-jacket and often uses Kevlar fibers as strength members, so even modest elongation of the jacket won't break the fiber. I've seen demonstrations where a piece of fiber optic cable is thrown over a busbar in a lab, and a heavy engineer hauls himself off the floor by the cable while the circuit remains completely operational.
Atlant 18:39, 11 October 2006 (UTC)
Great question. We really need a much more detailed and expanded section on fiber optic cable design (on my to-do list for way too long)
Atlant makes good points -- especially that the cable design protects the fibers. As for mechanical characteristics, you're comparing apples to, if not oranges, then pears. I'd say a lot depends on the copper pair count and the exact nature of the fault. Underground cables are more likely to get cut in the U.S. due to construction activity. Buried cables formerly were formerly considered more reliable than aerial cables,but the underground construction tempo has increased over the last two decades. Digging and drilling equipment will usually ruin either cable type with little effort. As for problems (storms, broken poles, etc) with either cable design installed aerially -- I'd say the survivability of either cable type will depend more on how strongly the cable is attached to the poles than on the particular cable type.
Then there are the very robust OPGW and ADSS cables used by power utilities. OPGW (optical groundwire) is essentially a metal conductor with fibers in it used as the transmission line's groundwire. ADSS (all-dielectric self-supporting) cable is a plastic-jacketted fiber cable but with much, much more aramid yarn (such as DuPont's Kevlar). Their much greater strength, combined with their location high off the ground on very robust structures makes ADSS and OPGW installations much more durable than traditional fiber or copper installations.
Fiber restoration used to take longer because the splicing equipment was expensive and scarce, as were fiber splicing crews. That's no longer true and I'd say you can nowadays restore a fiber cable faster than a high pair count copper cable that's been cut.
--A. B. 19:13, 11 October 2006 (UTC)
Thank you for meantioning backhoe fade; I clearly missed that point. One big difference worth mentioning is that often, when the backhoe wipes out the fiber, it takes a lot of capacity with it, whereas even a copper coax usually wasn't carrying that much traffic.
Atlant 19:24, 11 October 2006 (UTC)

[edit] Fiber-optic communication

It sounds like a lot of you have specialized experience that would be useful for improving the Fiber-optic communication article, especially the optical fiber section of that article johnpseudo 19:18, 11 October 2006 (UTC)

[edit] Raman Probes?

Should we perhaps mention that optical fibres are being used in Raman Spectroscopy probes or should that go in the Raman page? GreatMizuti 06:40, 13 October 2006 (UTC)

You could certainly make reference to that here and go into depth elsewhere.
Atlant 14:00, 13 October 2006 (UTC)

[edit] Laser Focus World and other publications

LFW added a link to Laser Focus World. This link was deleted as overly commercial and it's quite possible that it was added to enhance Laser Focus World's Google rankings more than the interests of Wikipedia. Nevertheless, putting aside my personal feelings about possible link-spammers, would links to a few industry periodicals such as Laser Focus World, Lightwave, fibers.org, Light Reading and/or others be beneficial to readers?
--A. B. 17:41, 13 October 2006 (UTC)

P.S. Interesting coincidence isn't it -- Laser Focus World's intials are also LFW.

(Speaking just for myself) I often find it difficult to decide what's linkspam and what isn't, and my opinion varies a lot depending on how big a Pandora's box I think we might be opening by admitting "just a little linkspam" into any given article. For example, on the hot tub article, I'm ruthless. Every #&##ed person with a hot tub shop or internet hot tub parts business seems to come along and think they can promote themselves there, so I routinely cut it all out. But if we had an obscure topic like (I'm making this up) "Neutrino communication networks" and there were one journal (say, Neutrino Trans-Planet Monthly) that is alone in covering the topic worldwide, then I at least would probably let that bit of spam stay; it would help someone who wants to learn all they can about neutrino communications networks.
Others doubtless feel differently.
With regard to this topic, I'm open to persausion either way. One of the ways that I'm negatively persuaded (BTW, hint to the spammer!) is just how many articles they feel the need to post their spam into. I'm also negatively persuaded when the spam is added by the party who stands to benefit from its presence (and no, logging out and spamming anonymously isn't going to fool anyone).
Atlant 17:51, 13 October 2006 (UTC)
I subscribed to LFW for years. It is not specific enough to fiber optics to qualify as a suitable Wikipedia external link on this article.--Srleffler 21:46, 13 October 2006 (UTC)
I don't disagree. What about Lighwave and fibers.org? --A. B. 22:17, 13 October 2006 (UTC)

[edit] Easy Reading

I'm in middle school and I have to do a one page report about optical fiber for science homework. However, checking out this Wikipedia article, I noticed a glaring problem: It's way to hard to read. There's too many technical terms for someone like me to understand! Could someone PLEASE make this article in Simple English form? I saw this was chosen as a good article, but I can't agree with that if I can't even understand half of what it's saying! 65.65.183.135 20:26, 22 October 2006 (UTC)Jimmie

I started a simple English article here.--Srleffler 23:44, 22 October 2006 (UTC)
I have the idea if it would make the article more accessible to general readers (non-physicists, non-engineers) to move the Priciple of operation section further down. Instead, start with an introductory overview, slightly longer than the lede, then History, then Applications, then finally Principle of operation and all the remaining setions. I'll start a draft of the introduction section at Talk:Optical fiber/Draft introduction. -- The Photon 01:56, 24 October 2006 (UTC)
I object to putting the history section directly under the intro. For articles on scientific and technical topics, the history of the subject is often of secondary importance compared to a description of what the thing is or how it works. The intro needs to be followed by a description of how an optical fiber works. What could work, though, is to start with a simple explanation, and move the technical details into a section further down in the article (after Applications). That would better meet the needs of the general reader.--Srleffler 23:47, 24 October 2006 (UTC)
I think you have to consider the audience. This article is of broad interest even to people outside of science and technology, as shown by the first post in this topic. To them, other things are more important than how it works. For example, how it affects daily life, the economic world, and how its used. I don't think the original poster really needed a version of the article that explained Optical fiber in simpler language; s/he just needed an article that emphasized what's really important about optical fiber to the whole world, before getting him/her lost in the details that are only important to technologists.
There are cases where I agree the "Principle-of-operation-first" rule would be best. One is when some detail of the physics is needed just to explain what it is, or how its different from other similar things. For example: Aspheric lens or Bipolar junction transistor. For optical fiber we can summarize the operating principle in one sentence: "it carries light from one end to the other." and have enough background to explain its important effects on everybody.
Another case is when the topic is so obscure that only readers who already have some background (or got lost) are likely to read the article. Again, the question that started this section shows that doesn't apply to optical fiber.
Another case is topics that are only notable (in the Wikipedia technical sense) because of their importance in technolgical or scientific context, like Gaussian beam or Snell's law. Once a topic is discussed regularly in Time magazine or daily newspapers, this doesn't apply and Wikipedia should have an article that addresses the topic in general terms.
Something I worry about is that many editors (not especially you) tend to think of Wikipedia as something that is there for our entertainment, and not something that's meant to provide information to the whole world. A second, more subtle, version of this is to think that all the readers will have the same priorities as us. Then we might think that the most important thing about optical fiber is that it works by total internal reflection, and not the fact that it has been part of reducing telecommunications costs dramatically, enabling wide access to the internet, increasing access to world-wide communications, and also enabling globalization of the economy affecting everyone in the world.
See Nuclear weapon for an especially egregious example of this. The device that created the cold war and set the course of the last 50+ years of history, starts with Types of nuclear weapons before going on to other topics. In that case I'm certain 90% of general readers would be beter served by a different arrangement, and the rest of us could still find the technical explanation if it were later in the article.
-- The Photon 02:18, 26 October 2006 (UTC)
I would be fine with having the Applications section follow the intro, provided the intro gives at least some idea of what an optical fiber is. I mainly just objected to the proposal to stick History right under the intro. I agree that a general audience may prefer to read about applications before the details of how it works. They are not likely to want to know the history of optical fiber in any detail before finding out what it is used for.--Srleffler 04:36, 26 October 2006 (UTC)

Thanks for the responses (not saying this this section is over or anything). Here's another thing I noticed about this article: Whenever it explained something using several technical terms, it would always try to explain what the term means using even more technical terms. That should really be fixed.

Thanks to Srleffler for making the Simple English version. I found it to be a lot better. There really are a lot of Wikipedia articles that need Simple English versions but don't have them.

And to The Photon: I'm male.

[edit] Is there anything "faster"?

ok, that may sound silly and irrelevant but it seems like useful information for an encyclopedia. are there other ways that can provide faster telecommunication? --87.194.72.129 01:33, 15 November 2006 (UTC)

Free Space Optics is about 50% faster.--Srleffler 02:27, 15 November 2006 (UTC)

hah, very interesting, thanks. (hm, i didn't know irda was part of that technology..) --87.194.72.129 01:19, 16 November 2006 (UTC)

[edit] Add image?

I was about to add this image that I created to the article:

Schematic of three primary modes for fiber optics: (going from top to bottom) multimode, graded-index, and single-mode. The refractive index profile of the fiber is shown on the left.
Schematic of three primary modes for fiber optics: (going from top to bottom) multimode, graded-index, and single-mode. The refractive index profile of the fiber is shown on the left.

However I didn't add the image, because it seems like the article already has quite a few images. I was worried that the article would become too cluttered. I would like a second (or third) opinion on this. —The preceding unsigned comment was added by Kebes (talk • contribs) 20:07, 3 January 2007 (UTC).

I personally really like this image - it explains a lot. I would support it being added to the article. fonetikli 01:56, 8 January 2007 (UTC)
Looks good to me. Put it near the top where there's plenty of room. Dicklyon 03:40, 8 January 2007 (UTC)

This is a great idea, and looks good. I think the illustration for "single mode" may be a bit misleading, however. It seems to show a single ray of light propagating straight down the center of the fiber, not even touching the walls of the core. Perhaps it would be better to draw it with the core smaller, so that the "ray" fills it. (In fact, the light propagating in a singlemode fiber not only fills the core, but extends beyond it into the cladding.) Also, the caption should be rephrased "Schematic of propagation in three types of optical fiber:..." to avoid confusion over the word "mode".--Srleffler 04:38, 8 January 2007 (UTC)

[edit] Pigtails

I often read about fiber-pigtails in connectors or isolators. Why are they not mentioned here? How can the modes be matched, if going from a fibre to a crystal (modulator, isolator, diode)? How can one make optical waveguides out of crystals? Are they all etched into the surface of large crysals with some doping to change the index of refraction? What if I do not want to dope? Arnero 19:52, 24 March 2007 (UTC)

If your crystal has a waveguide, like in a laser diode, you mode match with a tiny lens or other optics. If the crystal doesn't have a waveguide, you just use a lens to collimate the beam from the fiber. Waveguides are usually made in crystals by doping.--Srleffler 04:52, 31 October 2007 (UTC)

[edit] WDM

What about http://en.wikipedia.org/wiki/Wavelength_division_multiplexing

[edit] Please add info about color coding of cables/connectors

Quote (http://www.thefoa.org/tech/connID.htm): Color Codes: Since the earliest days of fiber optics, orange, black or gray was multimode and yellow singlemode. However, the advent of metallic connectors like the FC and ST made color coding difficult, so colored boots were often used. The TIA 568 color code for connector bodies and/or boots is Beige for multimode fiber, Blue for singlemode fiber, and Green for APC (angled) connectors.

I was looking for this info, but didn't find it on wikipedia.

[edit] Singlemode fiber

Under the heading "Singlemode fiber" it is said: "Fiber with a core diameter less than about ten times the wavelength of the propagating light...". The adjacent image (http://en.wikipedia.org/wiki/Image:Singlemode_fibre_structure.png) describes a singlemode fiber with a core diameter of 8 μm (and this is consistent with the fact that generally singlemode fibers have a core with a diameter around 10 μm). However, it means that this will act as a singlemode fiber for wavelengths more than 10 times longer, i.e. more than 80 μm (80,000 nm!). So visible (or near IR) light (say, 1,000 nm) will NOT regard this core as a singlemode core ?! In other words, according to the sentence cited above, a singlemode fiber with cutoff wavelength of 488 nm (I am using these daily) should have a core diameter of ~ 50 nm... Can anybody sort out this discrepancy?

--Microspot 06:10, 2 July 2007 (UTC)

The diameter of the fibre is 10 times the wavelength, so the 10 μm fibre can handle 1 μm wavelength, which is longer than visible light. I think you got the ten times round the wrong way. GB 09:15, 2 July 2007 (UTC)

[edit] Equipment costs to be added?

I think equipment costs for fusion splicing should be included in the article considering the pieces of equipment involved can exceed £50,000.

[edit] Optical fiber lifespan

what is the known lifespan of the optic fibre in different environments? —The preceding unsigned comment was added by 196.35.5.145 (talk • contribs).

With the exception of optical runaway PDF, I'm not sure there are any practical limits to the life of a passive piece of fiber optic cable. Cable with electrical repeaters would be a different story, of course.
Atlant 23:31, 15 August 2007 (UTC)
At least some cable is known to spontaneously break if you bend it, depending on bend radius, after some time (months-decades). The shorter the radius, the quicker it goes. In an ocean environment I think hydrogen contamination can occur (IRC), and that limits life.WolfKeeper 03:41, 31 October 2007 (UTC)

Also, Just a simple table showing maximum distances/bandwidth would be good. —Preceding unsigned comment added by 203.4.223.195 (talk) 06:54, August 30, 2007 (UTC)

That's a really complicated question, it depends on modulation technique, whether there is dispersion compensation on or for the cable, and whether you are using optical repeaters.WolfKeeper 03:41, 31 October 2007 (UTC)

[edit] 14 PB/s?

Um... source?

You can't just multiply the channels by 40G.... it turns out that the channels aren't actually independent, the fiber is not completely linear in several different ways, so there's intermodulation between different channels that tend to mess each other up. Even going from 10G to 40G you have to double the channel spacing. There's many, many complications.

AFAIK the current practical limit is more like 14TB/s or a factor higher, but not 1PB, that's currently out of reach, barring some breakthrough. And even ~14TB/s needs a large number of racks of lasers to get all the different channels lit, and there lots of couplers needed... all kinds of mess.

If it's not referenced it needs to come out.WolfKeeper 06:45, 31 October 2007 (UTC)

It looks like some theoretical number for the upper limit of a fiber's information-carrying capacity. Still, it's been marked "citation needed" for a while and it seems better to yank it out until a citable source can be found. 123davidn found a reference to that limit in a discussion forum posting, but that's not a citable source. I presume the discussion forum is not the original source, but that they may have seen the number quoted somewhere.--Srleffler 03:43, 1 November 2007 (UTC)

Uncited material removed from article:--Srleffler 03:43, 1 November 2007 (UTC)

In total, an optical cable can carry enough channels to carry data at rates as high as 14.4 Pb/s (circa 14 million Gb/s).

[edit] Brand-rex

Is brand rex a notable fibre producer? I found an abstract of Elliot's fibre optic cabling that mentions them, Previously I have read the book and recall is small, but full of good information for connecting, layout and routing of fibre, as well as other good things. I don't have the book on me at the moment, can anyone confirm if it is mentioned in Elliot's book? Abstract Fiber Optic Cabling, Second Edition (Newnes) ? A quick search seems to show lots of cabling connectors, more than fibres. User A1 (talk) 02:51, 17 November 2007 (UTC)

[edit] Merge with Colour coding of optical fibers

I oppose merging in Colour coding of optical fibers here. I'm not sure that material needs its own article, but it's too specialized for the article on optical fibers. Perhaps we need a article on optical fiber cables, which could incorporate that material and some material from this article.--Srleffler (talk) 02:24, 23 November 2007 (UTC)

That would work. We do need an article on optical fibre cabling. 132.205.99.122 (talk) 21:28, 23 November 2007 (UTC)
I support Srleffler's position and proposal. In fact, since it's more than a week since his comments, I'll make the new article at Optical fiber cable. The Photon 16:53, 1 December 2007 (UTC)