RE: PMD Equalization
To: Those members of P802.3ae who have information about fiber
design and manufacturing.
Please help me understand some issues.
1. If I look at all the singlemode fiber in the ground today, is it
fair to say that they can be put into two buckets - one with low PMD
of about 0.1 ps/sqrt(km), and one with high PMD, say, several times
larger? If yes, how much bigger is one bucket compared to the other?
2. Do those buckets correlate with dates of shipment - say, after
1992 and before 1992?
3. Do those buckets correlate with application - say, Undersea cable
and Metro/Access fiber?
4. Using 0.5 ps/sqrt(km) as an example, can I interpret it to be the
standard deviation of a distribution, therefore the peak-to-peak
value may be several times higher? If this were a Gaussian
distribution (I know it's not), I would then take 7 times sigma =
3.5 ps/sqrt(km) as its peak-to-peak value. Therefore, for a 49
kilometer link, the PMD peak-to-peak value will be 3.5*sqrt(49) =
24.5 ps. Is my understanding correct?
5. In some fiber data sheets, I see a note that says: "...fiber
specification supports emerging network design requirements for a
0.5 psec/sqrt(km) maximum PMD." Where is this design requirement
documented?
Thanks,
Vipul
vipul.bhatt@xxxxxxxxxxx
(408)542-4113
===========================
> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Chris Madden
> Sent: Tuesday, September 19, 2000 10:53 AM
> To: hbuelow@xxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
> Subject: PMD Equalization
>
>
>
> Henning,
>
> In your presentation to the 802.3ae September Interim on circuit
> implementation
> of a polarization mode dispersion (PMD) equalizer you
> showed pulse responses
> for 100km lengths of single mode fiber. Did you also
> characterize the PMD of
> these fibers using an interferometric method [ref. 1] or
> the widely-used
> Stokes
> Parameter Method [ref. 2]? Can you give some additional
> information on the
> type
> of fiber used in this work? The magnitude of PMD seems
> larger than expected.
>
> Thank you,
>
> Chris
>
> [1] Namihira, Y. and Wakabayashi, H., "Fiber Length Dependence of
> Polarization
> Mode Dispersion Measurements on Long-Length Optical
> Fibers and Installed
> Optical Submarine Cables", J. Opt. Communications,
> 12, 1, p. 2-9 (1991).
>
> [2] Poole, C. D., et. al., "Polarization Dispersion and
> Principal States in
> a
> 147-km Undersea Lightwave Cable", J. Lightwave
> Tech., v.6, no.7, p. 1185-
> 90 (1988).
>
> **********************************************************
> ******************
> **
> Christopher J. Madden, Ph.D. 3900
> Freedom Circle, Suite
> 200
> Principal Engineer/Scientist
> Santa Clara, CA
> 95054
> Fiber-Optic Data Communications Phone:
> 408.565.6857
> Tripath Technology Inc. Fax:
> 408.565.6850
> http://www.tripath.com
> cmadden@xxxxxxxxxxx
> **********************************************************
> ******************
> **