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[EFM] AW: Single wavelength, single fibre PMD for P2P

Hi Hans

I believe that the argument with fewer PMDs is that if the same
PMD may be used at the ONU for P2P and P2MP applications then this implies
fewer to track.  My response was that I believe it is a better solution to 
have an ONU PMD optimised for P2P, and this eliminates this argument.
Added to this, with optimised modules, a symmetric 1 wavelength system 
reduces the logistics as trhe same componet is used at both ends.

Inexpensive TOSA refers to the cost of the laser used in the module.

With temperature performance I was referring to changes in Popt over temperature, it being 
assumed that dispersion/wavelength losses have been accounted for. The wavelength
change over temperature question has been answered.

I agree with your point on parallel optics. However, I know that there is a huge
interest in this direction and EFM should benefit as a spin-off effect.

Regarding angle polished connectors, based on figures I have seen from existing fibre
networks, APCs are not necessary. Apart from that, the cost difference between
modules with APC compared to non-angle polished is minimal compared to the cost difference 
between FPs and DFBs, as would be required today with a two wavelength approach.

It is also feasible to use the same module for both 100 Mbps and 1 Gbps.
Yes, there is an over specification but the feedback I am getting in favour
of a 'no remote equipment change' upgrade is that a lot of people are interested.



-----Ursprüngliche Nachricht-----
Von: Hans Mickelsson (ERA) [mailto:Hans.Mickelsson@xxxxxxxxxxxxxxx]
Gesendet am: Donnerstag, 14. Februar 2002 18:02
An: '';;
stds-802-3-efm-p2p@xxxxxxxxxxxxxxxxxx; bob.barret@xxxxxxxxxxxxxxxxxx;
david@xxxxxxxxxxxxxx; doravv@xxxxxxxxxx; FEffenberger@xxxxxxxxxxxxxxxxx;
Hans Mickelsson (ERA); jradcliffe@xxxxxxxxxxxxxxxxxxxx;
jstiscia@xxxxxxxxxx; mark.sankey@xxxxxxxxx; meir@xxxxxxxx;
n.kleiner@xxxxxxxxxxxx; PengL@xxxxxxxxxxx; raanan@xxxxxxxxxxxxxxx;
rbrand@xxxxxxxxxxxxxxxxxx; sasaki144@xxxxxxx;
schelto.vandoorn@xxxxxxxxx; Tonyshouse@xxxxxxx; wdiab@xxxxxxxxx
Cc: Vipul_Bhatt@xxxxxxxx
Betreff: 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 be non-existing.

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 VCSEL?

"Leverage of 1310 nm....", True, but you raise an interesting question here. The use of parallel optics will be very difficult with any single fiber solution.

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]
> Sent: den 14 februari 2002 17:25
> To:;;
> bob.barret@xxxxxxxxxxxxxxxxxx; david@xxxxxxxxxxxxxx; 
> doravv@xxxxxxxxxx;
> FEffenberger@xxxxxxxxxxxxxxxxx; hans.mickelsson@xxxxxxxxxxxxxxx;
> jradcliffe@xxxxxxxxxxxxxxxxxxxx; jstiscia@xxxxxxxxxx;
> mark.sankey@xxxxxxxxx; meir@xxxxxxxx; Thomas.Murphy@xxxxxxxxxxxx;
> n.kleiner@xxxxxxxxxxxx; PengL@xxxxxxxxxxx; raanan@xxxxxxxxxxxxxxx;
> rbrand@xxxxxxxxxxxxxxxxxx; sasaki144@xxxxxxx;
> schelto.vandoorn@xxxxxxxxx; Tonyshouse@xxxxxxx; wdiab@xxxxxxxxx
> 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>>