As this is the start of another decade, I thought I’d begin by penning some thoughts on what might occur in the optical communications space in the coming year, a sort of Old Moore’s Almanack, complete with the usual predictions of a rain of frogs and the appearance of little green men in some remote area. However, it became apparent that it would be much more interesting to look a bit further ahead and think about what might happen in the next decade, as this gives time for some of the current research ideas to play out in the market. Before I begin, I must provide this important legal disclaimer: note that I am not obligating myself nor the Company to these crystal ball predictions as neither of us is licensed fortune tellers.
So, for what it’s worth, here’s Old Poole’s Almanack for what may be in store in optical communications in the twenty-teens.
1 Gb/sec to the Home
For those of us with long-term memories, it has been nearly 20 years since the introduction of the Hayes Smartmodem- the original 300 baud modem that kick-started the era of computer–to–computer communications. Today, 100 Mb/sec is becoming commercially available on an increasing scale. As communication bandwidth to the home has typically doubled every couple of years, then home bandwidth connectivity in excess of 1 Gb/sec is a shoo-in for 10 years from now.
Coherent to the Rescue
The rising demand for bandwidth in the home will, in turn, drive the need for more capacity in the backbone. As mentioned in a previous column, coherent transmission is coming soon to a system near you. Whilst significant (as opposed to bleeding edge) 100G coherent deployments are probably still a couple of years away, by the end of the decade, it looks very likely that coherent transmission in one of its various forms and flavors, will play a significant role in high speed communications.
The End of the ITU Grid?
Whilst I’m pretty comfortable about the first two predictions, a slightly more speculative prediction is that over the next 10 years we may see the beginning of the end of the rigid adherence to the ITU DWDM grid. The ITU grid was introduced in the mid 1990s when a high-speed signal was 2.5 Gb/sec and 100 GHz channel spacing seemed pretty dense. We are now reaching the point where 100 Gb/sec on 50 GHz channel spacing looks more like the norm in long-haul networks. Moving forward, however, it is clear that we will need to use the available spectrum within a fiber in an efficient as possible manner. This in turn will require the network to transmit low bit-rate signals in narrow channels and high-rate signals in broader channels. Whilst this approach is common in radio engineering where the issues of channel congestion have been around for many years, we are likely to adopt many of the techniques used there to maximize the capacity of a fiber network (and coherent modulation is just the first of these). Whilst this will require significant advances in Network Operating Systems to manage the complexity inherent in such an arrangement, many of the components required (i.e. transceivers with programmable data rates, Wavelength Selective Switches with variable bandwidth, etc.) are indeed already either developed or under investigation.
Next Stop: 400 Gb/sec/wavelength
Whilst we are still a couple of years away from 100G deployments, the debate has already begun over the next jump in transmission data rates – do we go for 400 Gb/sec or jump straight to 1 Tb/sec? Since the driver of telecom bit-rate is now the need to match the pipe-size on the big-iron core routers, we need to look at what the datacom guys are thinking. Here, it looks like the next step will be 400G, based on an extension of the 4×25 Gbaud multi-wavelength technology that is currently being developed for the CFP MSA. So, will we see 400 Gb/sec/wavelength telecom systems by 2020? Here, I’ll stick my neck out and say yes – we probably will as there are also strong technical reasons for increasing the per-wavelength capacity. However, the technical challenges to be overcome before we can get to this point are massive and will almost certainly limit any deployment to very high capacity backbone links, such as found along the US east coast and between the major cities in Europe.
Green is Good
Finishing up with another no-brainer – despite the atrocious failure of political will in Copenhagen, the need to use the finite resources of the earth more efficiently will become an even greater driver of innovation going forward. Optical communications, as has been shown many times, is by far the ‘greenest’ form of high-speed communications and will continue to be favored as we work to reduce our energy consumption per unit of bandwidth consumed. This will, in turn, drive new network architectures and routing algorithms that favor energy efficiency (and hence more optics) over existing ‘shortest path,’ hence router-intensive designs. Green is good for the planet and for those of us in the optical communications business too!
Well, that’s my two penn’orth – any additional predictions, or comments on the above, are welcome and greatly appreciated.
Events | Rafik Ward | 
February 25, 2010 12:37 pm | 
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