How to get 1 or 2Km of optical fiber?

David Landry dlandry at byu.net
Mon Mar 18 12:34:28 MDT 2013


D'oh, need to re-read what I send before I send it.
On Mon, Mar 18, 2013 at 12:24 PM, David Landry <dlandry at byu.net> wrote:

> On Mon, Mar 18, 2013 at 11:50 AM, Steve Alligood <steve at betterlinux.com>wrote:
>
>>
>> On Mar 18, 2013, at 11:18 AM, David Landry wrote:
>>
>> > On Mon, Mar 18, 2013 at 10:15 AM, Steve Alligood <steve at betterlinux.com
>> >wrote:
>> >
>> >> naw, you can get 32+ colors on a pair of single mode fiber, it just
>> isn't
>> >> cheap and has problems with different colors at different distances.
>> >>
>> >
>> > Maybe you can, but a single mode waveguide is designed to allow
>> propagation
>> > of a single mode at a particular wavelength. That wavelength of that
>> mode
>> > can be adjusted by changing core diameter and the index of refraction
>> > profile [0].
>> >
>> > I suppose you could couple other wavelengths into an evanescent mode
>> along
>> > the cladding over a short enough distance, though. Are you referring to
>> > some particular product?
>>
>> no, most dwdm and cwdm systems work with multiple colors across SMF.
>>
>> I have a set of Cienna chassis with four colors each from Provo to SLC
>> across a pair of SMF, and a passive WDM system (optics on their own colors,
>> with a shelf that is basically just a prism combining them) that goes the
>> same distance across a pair of SMF.
>>
>> As far as I know, SMF is the norm for most of my vendor's waves they sell
>> us across the country.  MMF just doesn't make sense for the distances.
>>
>> I am not an expert on how they combine, or the issues they have
>> amplifying the different colors, etc.
>>
> Thanks for clarifying. Thinking about it some more, I realized I misspoke.
> Keeping other things constant, you should be able to transmit wavelengths
> at least up to the V < 2.4 cutoff (above that, you might still be able to
> transmit, but it would definitely not be *multi-mode* anymore). I suppose
> the hard cutoffs are material-based.
>
I meant "single-mode".


>  BTW, anyone wanting to know more about fiber, read this:
>>
>>
>> http://www.nanog.org/meetings/nanog48/presentations/Sunday/RAS_opticalnet_N48.pdf
>
>
>  +1
>
> Nice set of slides, though I cringed a little where he said that
> "intensity" and "power" were the same; intensity has units of power per
> area (e.g. W/m^2).
> ---
> David Landry
>


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