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Re: [10GMMF] Task 2 and 4 Launch study group - table of primary and alternative launches vs fibre type

Dear all,
I am sorry that I was not able to join the last telco. The item was discussed maybe but I want to propose some change:
Central launch for OM1 fiber is stated with >35% in 5Ám radius. I would like to change that to the >30% in 5Ám as it was before.
1. The >35% coincide to the ideal calculated EFD for single mode launch with 5Ám offset. That is very tight! In a fiber stub which is used very often in single mode modules with central launch you will find more than a single mode and further you have to add some radial offset because of tolerances.
In a lens coupling you will have non ideal imaging on to the fiber endface and in addition again you have to add some offset tolerance. If you keep the figure at >35% than it is necessary to introduce additional effort in the construction and manufacturing of the coupling units (maybe it is necessary to exceed the standard single mode quality) to keep this tight tolerance.
2. It is appropriate to use the same single mode launch for all three fiber types. Why it is necessary to have a tighter tolerance for the OM1? The refractive index distribution is the same in the central region for OM1 and OM2 (the OM1 has just at a somewhat higher offset over the cladding), the manufacturing process is the same (as far as I know). I do not see any reason to have a different definition for the central launch for the 3 fiber types.

Therefore I would like to define the >30% in 5Ám radius and >80% in10Ám radius for the central launch for all fiber types.


Infineon Technologies Fiber Optics GmbH
Dr. Joerg-R. Kropp
Senior Staff Expert
Wernerwerkdamm 16
D-13629 Berlin / Germany
Phone -49-30-85400-4918
Fax     -49-30-85400-4900

-----Original Message-----
From: owner-stds-802-3-10gmmf@IEEE.ORG [mailto:owner-stds-802-3-10gmmf@IEEE.ORG] On Behalf Of Jonathan King
Sent: Samstag, 15. Januar 2005 04:32
Subject: Re: [10GMMF] Task 2 and 4 Launch study group - table of primary and alternative launches vs fibre type

Dear all
here is a revision of the table of recommended launches vs fibre type, following comments and discussion on the Jan 12th call, I've added in the alternative launches and EF definitions, including the revised EF radii noted by David Cunningham in his comments to Draft 1.0

Please let me know of any errors or comments you have as soon as possible before the next call (Weds 19th Jan).

many thanks


tel: 1 408 524 5110
fax: 1 408 739 0568

Jonathan King
Director, Optical Systems
BigBear Networks
345 Potrero Avenue
Sunnyvale, CA 94085