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Dear all, I have recently joined this reflector, and I would like to make one
observation which may be of benefit to the group. However, please forgive me if
I speak out of turn, am confused about some of the acronyms or cover material
already agreed. There appears to be some considerable debate relating to the trade-off
between reach, data rate, buffer requirements and the capabilities of electronics
with manufacturability at a reasonable cost. This has lead to the M lanes at I would like to propose the HSSG to consider the use of a new
modulation format, currently known as “Coherent WDM”, in order to
simultaneously meet all of these requirements. In Coherent WDM, we use a single
laser source, minimizing inventory. This source is either a mode locked source,
producing multiple carriers, or a standard cw source followed by at least one
sine wave driven modulator (10 GHz in this example) in order to generate an
optical carrier for each lane. These carriers are then modulated using an array
of modulators (one for each lane, and each driven at 10 Gbit/s in this
example), with, for example, a PIC similar to the one proposed by Drew Perkins.
This produces a single 100 Gbit/s (in this example) signal, occupying a small
spectral width of very close to 110 GHz which is transmitted as a single entity
over a link (either point-to-point or a WDM network). The compact spectrum and
careful design of the PIC and drive circuits combine to give negligible skew
between the lanes, minimizing buffer requirements. You thus obtain the key
features of the high serial data rates. It has been demonstrated that the reach
of a Coherent WDM system is dominated by effects proportional to the data rate
of each lane rather than the total data rate, and 10 Gbit/s electronics may be
used. You thus also obtain the key features of a high lane count, low serial
data rate link. I would be very happy to provide further details of Coherent WDM
should anybody reading this contribution feel that it is appropriate. Thank you for your attention Andrew Ellis Senior Research
Fellow Photonic Systems
Group Tyndall National
Institute and Department of Physics Phone: +353 21 490
4858 Fax: +353 21
490 4880 e-mail: andrew.ellis@xxxxxxxxxx web site: www.tyndall.ie/research/photonics-systems-group/index.htm |