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Technology Stocks : Ciena (CIEN) -- Ignore unavailable to you. Want to Upgrade?

To: jghutchison who wrote (9961)	12/12/2000 1:13:04 AM
From: mact	Read Replies (1) \| Respond to of 12623

As the channel spacing narrows, its ability to carry the bit rate is reduced. In theory, a 1G channel spacing is limited to a 1G bit rate. The bottom line is that we are quickly approaching fundamental limits of bandwidth over fiber. Ciena has announced that it will have a 320 channel system next year using its proprietary Bragg fiber grating technology. perhaps we are approaching the limits bandwith per fiber but prob. not...new tech's emerging everyday...by next yr, avnx and other vendors will offer 800-1000 channel systems that will carry 2.5Gbps each...with 860 fibers per cable, bandwith will be plentiful...matter of fact, it will be in the petabit/sec range, which is close to the total internet traffic per month just a yr or two ago...avnx and other co's also working on RF sub-channels that will split the lambda another 100-1000 fold...and with tunable lasers on the horizon by altitun, new focus and several others, bandwith might get so plentiful that the need for pure optical switches might not be needed as much...also, imo fiber-bragg, thin film filters and awg tech. has limitations...i think fabry-perot inferometer techn. has advantages. mact

To: jghutchison who wrote (9961)	12/13/2000 1:58:44 AM
From: jeremic	Read Replies (2) \| Respond to of 12623

Jack, It is a 'fundamental limit' that as you reduce channel spacing bit rate is concomitantly decreased. However, you're confusing overall bandwidth with the capacity to pack bit rates on wavelengths. That is only one way to do it, the other possible solution is to limit bit rate per channel (say 1Gb or even 100MB) and increase channel count - the result is the same: improved bandwidth. I believe network architecture will be much more flexible and adaptable if the latter solution is promoted. The fundamental limits of bandwidth will be encountered much sooner if bit rate is the only concern. You're mention of Ciena's Fiber Bragg gratings does not address the advantages of the combination of Avanex's PowerMux/PowerShaper which uses the combination of improved channel shaping and the Fabry-Perot interferometer to align wavelengths based on frequency interference rather than the tricky (and limited) spatial alignment of Bragg gratings. Your assumptions regarding channel spacing are based on the inherent limitations of gratings and don't include the radical approach developed by Avanex. For someone who follows optics as much as you, I'm surprised you've been so dismissive of AVNX, regardless of Gilder. FWIW jeremic