Dear all,
Maurice (thanks for very detailed comments
and suggestions) suggested to divide the Task3 discussion into separate 2
threads. I belive that is a good point.
Here are once again my questions and the
answers I received so far. I will use tags with names to indicate comments in
the main question body.
1.
The issue of transmitters for OLT and
ONU. In the OLT we will probably need to have an externally modulated laser,
possibility with a post-amplifier if we want to have increased split ratio at
standard transmission distances. What kind of amplification technologies do You
see as viable for 10GEPON systems ? EDFA's may proove too expensive, Raman
amplifiers are bulky so we are generally left with SOAs, unless I missed
something. Does anybody have any data / presentation / would like to prepare a
short review of the existing amplification techniques and laser sources for the
OLT side ?
<Marek> I would appreciate some
comments for this issue as well. We will have at least to examine the existing
and commercially available amplifiers. I think we will not have time to go into
examination of new research stage solutions like QD amplifiers etc. </Marek>
2. The same goes for the ONU side - we need to know what type of lasers we can use in the ONU in the light of the increased loss budget of >= 29 dB for high split ratios and standard 10/20 km transmission reach. Are we limited to ONU side amplifiers or should we rather concentrate on the OLT side preamplifier ? What is Your opinion ?
<Maurice> Quantum efficiency in visible light LEDs, Lasers and other light-emitting optical components is also going up at about 1-2dB/18 months according to some publications that I have seen. Again, there are components which could "meet standard in the future if you plan carefully" Please consult others before casting any numbers in stone. My numbers may be wrong, or there may be a technological roadblock ahead too. </Maurice>
<Marek>In other words, we can be looking at a next generation of
laser sources by the completion of 802.3av standard. The question however
remains. Is it possible to achieve >=29dB budget without amplifiers at
the OLT side. The point here is that the as hoc should examine high split
count systems, where the channel insertion loss oscillate around 29dB,
meaning that the ONU lasers have to bypass this kind of loss. What do You
think is a better solution:
- application of amplifier at the ONU + lower power laser
- high power laser at the ONU and no amplifier
- lower power laser + preamplifier at the OLT</Marek>
Best
wishes
Marek
Hajduczenia (141238)
(PhD
Student - COM RD1)
SIEMENS Networks S.A. - IC
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Marek.Hajduczenia@siemens.com
http://marekhaj.easyisp.pl/index.php
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