A Yuletide Request from Optics Researchers: All I want for Christmas is…

As the festive season drags us kicking and screaming into rounds of seasonal silliness (and if you’ve never seen a man in a false beard and Santa Suit surrounded by fake snow in 40 degree heat (100F for the renegade non-metrics out there) you haven’t lived) it’s time to hope you’ve been a good person and send that letter to the North Pole and hope that the man in red can make it through the air conditioning vents and deliver something for all those of us who work at the optical layer. I’m therefore making three Christmas wishes for developments from our researchers worldwide.

Better fibres, please.

Silica is a wonderful material and we all love it dearly for its incredible transparency, strength and (now we know how to do it) ease of processing. However, it still isn’t ideal. It does have some loss and, possibly even worse, has a level of non-linearity. The combination of the two means that we still don’t have the perfect transmission medium. So my first Christmas wish is for a fibre which has zero loss and no non-linearity. Maybe some of the hollow-core Photonic Crystal Fibre designs that have been proposed will get us there in the end, but I haven’t seen any signs of real progress towards practical, manufacturable designs which could be useful in a real-world transmission system. Since we will therefore always have some form of loss, this leads to my second wish…

More Gain.

Since we don’t have zero loss fibres, we need optical amplifiers. As an industry, we have been incredibly fortunate that the EDFA gain region and the minimum loss window of silica coincide so well. This has supported the development of DWDM systems in all their shapes and sizes over the past 25 years. However, as we keep pushing system capacity, we’re running out of gain in the EDFA (even allowing for L-band) and having to drag Raman amplifiers kicking and screaming into the mainstream of technology. However, Raman amplification has its own issues (particularly noise figure) and what we’d really like is an amplifier with 0dB noise figure, 30+ dB of gain, saturated output powers of >+20dBm and operating over a 200nm bandwidth. Phase Sensitive Amplifiers show some promise here, although the technology is still very immature and is unproven at a network level.

Polarisation be gone.

With the imminent introduction of coherent transmission systems, Polarisation Mode Dispersion (PMD) will no longer be the bugbear it was for high-speed 40G systems. However, our old friend PDL (Polarisation Dependent Loss) now becomes a limiting factor, so my final wish is for optical components with no PDL (or Polarisation Dependent Gain – PDG).

I am sure there are other things we could wish for– let me know your thoughts and suggestions.

In the meantime, have a cool yule and a restive festive.

Optical Components: Reasons to be cheerful

Guest blog by Pauline Rigby, editor of Opticalreflection.com

I set out for the European Conference in Optical Communications (ECOC) in Turin this month with an open mind. The amount of data in the digital universe may be growing at a phenomenal rate, but are the fortunes of optical components vendors on a corresponding upwards cycle?

I was pleasantly surprised to find a very positive vibe on the show floor. Industry consolidation, oversupply and commodity products are no longer the main topics for discussion. Instead vendors are talking about how to differentiate their offerings, and some are even complaining that they can’t keep up with demand. There are several names that could fit the bill here, but since this is a Finisar blog, I’ll talk about Finisar. [Ed note: good idea!]

Just a few weeks prior to the show, Finisar announced Flexgrid technology for its wavelength selective switches (WSS), which allows telecoms carriers to define wavelengths that don’t conform to the ITU grid. Flexible channel spacing will probably be needed to accommodate future bit rates such as 400 Gbps or even 1 Tbps, which will occupy a non-standard amount of space. For instance, a 400 Gbps channel might take up 75 GHz of bandwidth, while 1 Tbps could occupy 150 GHz.

Verizon executives explained at ECOC how they will need this flexibility in order to ensure their networks are ready for 1Tbps upgrades, which are likely to be needed during the working lifetime of WDM equipment being designed today. Finisar’s WSS technology, which is based on that found inside digital projectors, has an advantage because it can easily be programmed to accommodate different channel spacings – it’s simply a software change.

The cold, hard data suggest that the components industry is on an uptick. In the couple of weeks since the show there have been no fewer than three positive market forecasts from research firms, including iSuppli, LightCounting and Infonetics, but my favourite data point comes from Andrew Schmitt, directing analyst for optical at Infonetics Research, who spoke at the ECOC Symposium on 100GbE.

The market for optical hardware is pretty substantial, and currently worth £13 billion annually, according to Infonetics. The spending patterns in this market are shifting away from legacy Sonet/SDH hardware and towards WDM equipment. Right now the balance is about 50:50, but by 2014 the market will be roughly 70% WDM equipment.

“This is very good news for components vendors because the bill of materials [for optical components] is much higher in WDM systems,” Schmitt pointed out. “While the overall [optical hardware] market is growing at around 5% annually, if you’re making components your market is growing at closer to 10%.”

Pauline Rigby is editor of the blog Opticalreflection.com

Future Proof Your Network: Flexible Grid Architecture

The driver for any development in optical communications technology is, almost without exception, a reduction in cost-per-bit/km travelled (although there’s one interesting exception to this which I’ll talk about at some future point). This intensely capitalistic and utilitarian approach has enabled the dramatic growth in the internet (YouTube needs very low cost/bit to be viable), but are we approaching the point where the rate of cost reduction may start to slow down? In the US, for example, there’s recently been a move away from ‘all you can eat’ data plans to something approaching (very slowly) the capped plans found in many other parts of the world – partially in response to the recognition that there is a finite amount of bandwidth available at any point in the network.

In the optical space, we have, over the past 15 years, moved to higher and higher per-channel bit rates running on more-closely-spaced WDM channels. However, we are (as I mentioned previously) reaching the limit of what can be achieved on the ITU Grid-based systems introduced in the 1990s. Consequently, fibre bandwidth, which only a few years ago was being proselytised by Gilder as being effectively ‘infinite’, is increasingly being seen as a finite resource which needs to be managed as effectively as possible using all the techniques at our disposal.

One solution, which is gaining a great deal of traction at the moment is to move away from the constraints of the ITU Grid to what we term a flexible grid architecture where the channel optical bandwidth can be dynamically adjusted to meet the requirements of the signal being sent through it and hence maximise the data carrying capacity of the fibre.

This ability to control the channel bandwidth and position with GHz resolution has been utilized in many research papers as I discussed in my previous blog. In practice, however, the complexity of managing a network with such fine granularity may outweigh its advantages. Market requirements indicate that a channel bandwidth granularity of 12.5 GHz will meet future channel bandwidth requirements and that even 25 GHz channel bandwidth increments may be sufficient.

First generation WSS (typically based on MEMS and/or Liquid Crystal technologies) allocate a single switching element (pixel) to each channel which means that the channel bandwidth and centre frequency are fixed at the time of manufacture and cannot be changed in service. However, second generation WSS, based on Liquid Crystal on Silicon (LCoS) or 2D MEMS mega-pixel matrix switching arrays, permit dynamic control of channel centre frequency and bandwidth through ‘on the fly’ modification of internal pixel arrays via embedded software.

Furthermore, not only must the core switching elements in a ROADM be capable of supporting flexible grid architectures, but the multiplexer/demultiplexers and filter arrays must support the same degree of flexibility. The flexibility provided by LCoS technology can also be applied to these high-port-count (e.g. 1×23) multiplexer/demultiplexers and programmable filter arrays.

This discussion has focused on the requirements for the wavelength-selective elements in a flexible-grid ROADM as these will be the first part of the flexible grid network that has to be deployed to ensure the network is future-proofed. However flexible grid networks will also require additional component developments including scanning optical channel monitors capable of handling polarization multiplexed signals with varying bandwidths and signal formats and signal (and local oscillator, for coherent systems) lasers capable of operating at the finer frequency increments implied by flexible grid architectures (6.25 GHz for 12.5 GHz channel increments and 12.5 GHz for 25 GHz channel increments). This provides a continuing challenge to those of us in the optical space as we continue to improve the price/performance of our components and modules which underpin the networks of the future.

Flexible grid technology (not grid-less) will allow the optimum usage of the finite operating window in a fibre and allow operators to continue down the path of reducing the cost per bit/km of data travelling through the network.

Any comments are welcome.

Sensors Expo Wrap-Up

This week’s Lightspeed post comes from guest blogger Pritha Khurana, Components Product Line Manager for Finisar.

The last few weeks have been very busy for Finisar. Spread across the world, our team participated in both the ISC and Sensors Expo conferences. I flew to Chicago to spend June 7 through June 9 at the annual Sensor event, co-located with the Embedded Systems Conference (ESC). I love the opportunity to reconnect face-to-face with our customers and partners, discuss fiber optic communication advances in the enterprise with our industry colleagues, and of course the chance to meet potential customers. At this event, Finisar showcased its VCSEL technology – used for precision optical sensor applications – at the company’s booth. Finisar’s demonstration of precision velocity sensing using VCSELs for a completely non-contact system drew a lot of interest. A number of customers expressed an interest in turbidity sensing using lasers as well.

I spent two solid days meeting with customers and partners at this year’s Sensors conference, which drew more attendees than last year. The sensors industry, a space Finisar is engaged in through its VCSEL products has widely embraced the areas of MEMs-Based Systems, Energy Harvesting, Smart Power, Data Acquisition, Wireless Networking, and more.

While a busy couple of weeks for Finisar, the time with our customers, partners and industry peers discussing “what’s next”, and discovering how Finisar is an important facet of these next steps was as valuable as ever.

ISC 2010 Wrap-Up –What’s Hot in Supercomputing

This week’s blog post comes from Katharine Schmidtke, Finisar’s Strategic Marketing Manager.

I had the pleasure of attending the International Supercomputer Conference (ISC) event May 31-June 3, in Hamburg Germany. The show was well attended and appeared to have doubled in size from last year. In attendance were all the major industry suppliers and leading technology providers such as Mellanox, QLogic, Voltaire, NVidia, HP, IBM, Cray, Oracle, AMD, Intel, LSI, Supermicro and STEC. Key themes included supercomputing, storage and networking. Of those, hot trends discussed were cloud and parallel computing as well as the future developments to come in the next 10 years. The trend to higher bandwidth continues, with the IBTA announcing the latest roadmap which adds a new datarate at FDR (14 Gbps) in addition to EDR (26 Gbps). InfiniBand is targeting 300 Gbps by 2011 in a 12 lane format running at 26Gbps per lane.

And as I sat through the presentations and spoke to some of the folks on the show floor, it became evident that there are two central themes underpinning all the major business and HPC initiatives – latency and flexibility. Reducing latency is key for supercomputers, while flexibility is the driver in cloud computing. NVidia made quite a splash with their Tesla C2050 GPUs which are used to improve data crunching speeds in many supercomputers, including the new #2 supercomputer – the Nebulae system built by Dawning in China. Dr. Wilfried Oed from Cray shared some of the secrets in the new XE-6 supercomputer including the new Gemini network card which he admits is “more than just a router” by increasing processing speeds using a clever non-blocking routing system.

On the news front, the biannual 35th edition of the Top 500 supercomputer list was released. The U.S. continues to take the lead in the number one spot with Jaguar, the fastest supercomputer system used for The Department of Energy’s Oak Ridge Computing Facility. Trailing close behind and ranked second on the list is Nebulae, China’s fastest system worldwide.

Other noteworthy technical initiatives point to Intel, who dominates the high-end process market with roughly 82% of all systems and over 90% of quad-core based systems. IBM recoups the lead in market share by total systems and overall performance from Hewlet-Packard (HP). And exciting for Finisar – we were part of the 120 Gb/s InfiniBand demonstration at this year’s event. Check out the press release issued by the HPC Advisory Council to learn more.

Until next year’s ISC show, Auf Wiedersehen, as they say in German!