[EFM] RE: Single wavelength, single fiber PMD for P2P
Single wavelength will require network reflections (ODN-ORL) better than
20 dB. Most carriers we spoke to expressed confidence that the network
in place are 20 dB worst case, and newer installations are better, ALL
with regular connectors. What is your experience?
DFB have more issues operating over extended temperature range (cost of
From: Hans Mickelsson (ERA) [mailto:Hans.Mickelsson@xxxxxxxxxxxxxxx]
Sent: Thursday, February 14, 2002 9:02 AM
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Subject: RE: Single wavelength, single fibre PMD for P2P
Good work, see below for some comments.
"Fewest variations of PMD to track in field". I agree that it will be
less PMDs to track however if this is a real problem is not clear.
Assume that you decide to use a certain lamda for downstream then it it
ijust to follow this approach in all your switches and the problem will
Can you explain "Use of inexpensive TOSA a bit further"?
"Temperature performance". An un-cooled DFB (0.01 nm/K) is less temp
dependent than a FP (0.03 nm/K). Can anyone give some figures for a
"Leverage of 1310 nm....", True, but you raise an interesting question
here. The use of parallel optics will be very difficult with any single
Some othe options to consider are;
The need for angled polished connectors for controlling refelctions in
the network. Not necessary for dual but probably necessary for single.
Will the be any difference between the two options in an up-grade
scenario to higher bit-rates?
> -----Original Message-----
> From: Thomas.Murphy@xxxxxxxxxxxx [mailto:Thomas.Murphy@xxxxxxxxxxxx]
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> Cc: Vipul_Bhatt@xxxxxxxx
> Subject: Single wavelength, single fibre PMD for P2P
> Hello All,
> First off I apologise for a blanket bomb approach with
> sending out this e-mail but
> I have my reasons, as will become clear below.
> As most of you will know, I am currently co-ordinating the development
> of a single fibre, single wavelength PMD proposal for P2P links.
> During a recent discussion of this work, it became clear that
> a number of people
> were unaware of what was happening or still unclear of some
> of the technical issues involved. Several questions arose
> which had already been answered in the course of dedicated
> telephone conferences and
> some new issues were also raised.
> Of course this discussion is very good for the quality of the
> standard. However,
> in the interest of progress and completion of a baseline
> proposal for March, it
> is essential that people allay any concerns they may have in
> the interim and go
> into the meeting feeling ready to make an informed decision.
> I would therefore ask people who have an opinion (or concern)
> in this direction
> to speak up, raise the issues and avoid further surprises in St Louis.
> Arising from the aforementioned discussions was the idea that
> a 2 wavelength
> PMD may be an alternative approach. In order to facilitate
> comparison of the
> two ideas, a matrix was proposed which I have included here
> in a somewhat modified
> form. I divided the table into Today and Future, the former
> represent current laser sources (FP and DFB)
> and the later assuming the use of VCSELs, be that at 1310,
> 1490 or 1550 nm. I dislike the 1-10
> approach of comparing as this is too subjective, rather a
> binary 0 or 1 representing the better solution
> for a particular criteria. In some cases there are no
> differences and both receive 0. The 'points'
> are added and a comparison may be made. NOTE, this will not
> be the basis of the decision, rather an aid
> to objective comparison. I have included comments behind each
> issue cells detailing my evaluation.
> So, speak up, play with the table, add issues if necessary,
> send it back to me,
> get on the telephone conferences.
> Best regards and looking forward to further progress.
> Tom and the P2P group
> <<Comparison matrix for 1 and 2 wavelength PMDs.xls>>