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My primary concern is that the 1577 nm downstream
wavelength is inconsistent with use of the 1550 nm broadcast (auxiliary)
wavelength. The problem is that the two wavelengths are too close together
to allow us to build economical filters at the ONU to separate the two
wavelengths. It is a little easier with the 1590 nm wavelength, though it
is still difficult. Originally I wanted to specify the wavelength band as
1580 - 1600 nm as it was originally. But I found that when I put in real
filter characteristics, I still had an extremely narrow transition region for
the filter. So I accepted that we would have to narrow the transmit
window. I chose +/-3 nm (1587 - 1593 nm) following the reasoning for
PR(X)30. We are adding cost to the laser, but at the OLT, which is not as
cost sensitive as is the ONU.
I also had to accept that the auxiliary wavelength was
limited to 1550 - 1555 nm, even though commercial practice is to use wavelengths
up to almost 1560 nm. People may complain about this restriction, but I
think in the end they will live with it.
Unfortunately I have not been able to get quantitative
information on the filter complexity - I would like to see filter vendors jump
in with comparative numbers. Some vendors I spoke with gave me more
pessimistic numbers than I used in preparing the slides.
So the application is for anyone who wants to use the 1550
nm broadcast wavelength. This is the only way I see to possibly make use
of 1550 nm overlay practical. And it still demands a more difficult filter
than we demand currently. But presumably advances in the state-of-the-art
will made the filter practical at some point.
Thanks,
jim
Jim Farmer, K4BSE
From: Frank Chang [mailto:ychang@xxxxxxxxxxx] Sent: Wednesday, November 05, 2008 7:06 PM To: STDS-802-3-10GEPON@xxxxxxxxxxxxxxxxx Subject: Re: [8023-10GEPON] FW: Downstream wavelength I just reviewed this
thread, and my interpretation to Jim?s slides is that-
1)
The
argument is not for PR(X)30 as cooled TX is assumed because of tight power
budget, so narrower 1577nm band considered feasible for PR(X)30.
2)
For
PR10/20, possibly uncooled optical sources are assumed, so bring about the
argument that larger wavelength band, such as wider 1590nm band, is only
feasible. To satisfy this
argument, basically call for the group to switch back to the wavelength plan
originally specified in D2.0. So actually we are re-visiting the argument the
group made during the baseline stage a year ago. Jim- Can you confirm
this is what you are looking for? As it is clear the
PR(X)30 will be assumed mainstream deployment which requires co-existence with
installed 1G version, can anybody elaborate the scenarios on how PR10/20 going
to be deployed? My question is weather PR10/20 scenarios has to use cooled or
semi-cooled optical source?
] thanks Frank C.
From: Frank
Effenberger [mailto:feffenberger@xxxxxxxxxx] To pile onto this
thread, I have a question regarding Jim Farmer?s most recent presentation and
Maurice?s support of it: Did you notice that
Jim?s presentation is asking to change the PR10/20 OLT transmitter wavelength
range to 1587 to 1593nm? (At least, that is how
I read it, but I should say that the exact numbers are not clear.)
Perhaps Jim can clarify
exactly what he is asking for? that would be helpful.
Sincerely, Frank
E> From: Marek
Hajduczenia [mailto:marek_haj@xxxxxxx] Hi Maurice,
Just following the
arguments You used in Your email: does that mean that You see PR(X)20 OLT
transmitters as uncooled devices? Are the power levels we are targeting
achievable using uncooled optics? As far as I understand, cooling is necessary
not only to keep the central wavelength within the predefined range but also
assure higher output power level. Can You comment on
this? Regards Marek From: Maurice
Reintjes [mailto:maurice.reintjes@xxxxxxxxxxxxx]
We request to make the attached
presentation during the 10GEPON meeting in Thanks, Jim Farmer, K4BSE |