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Hugh Rich Taborek made several presentations
proposing an optical PAM scheme during the HSSG led by Jonathan Thatcher that
became the 802.3ae project. Bruce Bruce Tolley Vice President of Marketing Solarflare Communications 9501 Jeronimo Road, Suite 250 IP phone: 949-581-6830 extension 2014 Fax: 949-581-4695 mobile phone: 650-862-1074 btolley@xxxxxxxxxxxxxx From: Hugh Barrass [mailto:hbarrass@xxxxxxxxx] Andrew and others, 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 |