SC10 and Optical Transcievers

It’s a beautiful time of year in New Orleans for the top supercomputing companies to show their wares. While I wouldn’t consider SC10 exactly the place to sell optical components, there were a few new developments there. SCinet – the network that is always built at the top HPC conference – boasted 100G Ethernet as well as OTu4. Alcatel-Lucent, Ciena, Cisco, Force10 and Juniper, among others donated equipment to build this network. Module vendors Avago Technologies, Finisar and Reflex Photonics contributed QSFP and CFP 40G and 100G devices to the cause.

Meanwhile, the Ethernet alliance was showing two demonstrations in its booth – a converged network running FCoE and RoCE over 40GigE and 100GigE. Nineteen different vendors participated in this demo that was run by the University of New Hampshire Interoperability Lab. Both CFPs and QSFPs were used in this demo.

Some of you may wonder why I would attend SC10. I keep my eye on the HPC market because it usually indicates where the broader data center market will be in a few years. And, in fact, even medium-sized businesses’ data centers with higher computational needs are starting to resemble small HPC centers with their server clusters using top-of-rack switching.

Most of the top optical transceiver vendors and even some of the smaller ones see this market as an opportunity as well. While InfiniBand still uses a lot of copper interconnects, for 40G and 120G, this is changing. QSFP was the standout for 40G IB displays and CXP AOCs were shown for 120G as well. Avago Technologies was the first to announce a CXP module at the show.

Some believe that the CXP will be short-lived because there is progress being made on 4x25 technologies – Luxtera announced its 25G receivers to go with its 25G transmitter that it announced earlier this year. But it will still be a few years before all of the components for 25G will be ready for system’s developers to spec in. Tyco Electronics had a demonstration at their booth showing it is possible to run 28G over eight inches of a PCB, but this was still a prototype. And Xilinx has announced a chip for 28G electrical transceivers that can be used with this board design. But, none of these devices are even being tested by equipment manufacturers yet and the CXP has already been adopted by a few. So I think the CXP may have more life in it than some people may think.

DARPAs Ultraperformance Nanophotonic Intrachip Communitcations (UNIC)

UNIC is a DARPA-funded project that started in 2008 and is slated to run for about five years. Sun/Oracle, Kotura and Luxtera are working to develop this chip-to-chip "high-performance, CMOS-compatible photonic technology for high-throughput, non-blocking and power-efficient intrachip photonic communications networks."


The first application of such technology is targeted for optical interconnects for microprocessors. The goal is to replace high-performance computing clusters with computers that consist of these arrays of microprocessors interconnected by optics. Another goal of the project is to make sure the new devices are "compatible" with CMOS processes in order to also integrate the associated electronic devices. Using its now proven Silicon CMOS Photonics technology, Luxtera has developed transmitters and receivers for the project. Kotura supported the project with new low-power, high-speed modulators made of silicon photonics.


Potential new products are expected by the end of 2012. While these will be initial products, commercialization is not expected until quite some time later, perhaps not until 2016 or so. Meanwhile, Luxtera will continue to use its technology to sell 10, 40 and 100G transceivers and AOCs.


With data rates increasing beyond 10G, chip-to-chip, on-board and board-to-board optical interconnects will become progressively more significant. Even at 10G, traditional printed-circuit boards cannot support transmission beyond about 12 inches without needing re-timers. As I’ve mentioned in previous posts, instead of spending money to develop more exotic PCBs using complicated digital signal processing (DSP), it may be time to embrace optical interconnects for both board-level and chip-level.

25G/40G VCSELs Driving Short-reach Optical Interconnects

Just a few years ago, laser designers were struggling with stability of their 10G VCSELs. But now, at least one, VI Systems GmbH, claims it will have production-ready 40G VCSELs within the next few years. The German start-up has developed two products it believes will take VCSELs beyond 10G applications - a directly-modulated (DM) device and an electro-optic modulated (EOM) DBR VCSEL. Both are short-wavelength (850nm) lasers.

In a recent press release, VI Systems explains that it “developed the VCSEL products at a wavelength of 850 nm along with a range of extremely fast integrated circuits based on the SiGe BiCMOS (silicon-germanium bipolar junction transistors in complementary metal-oxide-semiconductor) technology. The company uses a patent pending micro-assembly platform for the integration of the opto-electrical components and for alignment to a standard high performance multi-mode glass-based fiber.” The start-up has been presenting data supporting its claims of highly stable devices for more than a year now. It gets there by changing the laser active region material and structure to InAs quantum dot (QD).

Not only is VI Systems working on innovative laser structures, it has also developed new electro-optic integration methods to further reduce the cost of these devices.

I’ve noted in previous posts how VCSELs are the key to low-cost optical networks in the data center. These new VCSELs and packaging methods would bring an even more cost-effective “serial” solution for 40/100G. They could also be used for very short-reach optical connections like for chip-to-chip, on-board or board-to-board. Perhaps these inventive products will rival Avago’s MicroPOD and Luxtera’s OptoPHY (also in previous posts). Based on the presentations that VI Systems has released, it sure appears that its management completely understand the needs of both the data center and optical interconnect markets so could very well give incumbents in the industry some competition.

Optical Engines

I was reviewing some research I recently conducted for the Optical Interconnect report I wrote for CIR and realized that I hadn’t yet “blogged” about what I would consider some exciting new product directions that many optical components suppliers are taking. We’ve been talking about optical integration for many years and some companies, like Infinera, have actually implemented it into their real-world products. But there are more cases of this than ever before and I think we’re on the brink of some true industry breakthroughs using what many have deemed “optical engines.”

Here is a summary of the component companies and their associated optical engine products:

• BinOptics – it uses its InP PICs to build "custom integrated microphotonics solutions" for its customers
• ColorChip – its silicon photonics is at the center of its 40G QSFP modules
• Lightwire – its Opto-electronic Application Specific Integrated Subsystem (OASIS) promises low power and higher density
• MergeOptics/FCI – OptoPack is at the center of its 10G and above transceiver designs
• Reflex Photonics – LightAble is the building block for its transceiver modules
• Santur – DFB/waveguide architecture has promise for not only tunable lasers, but many different optical interconnects

So what’s the big deal? In the past, optical integration was a science project looking for an application. Now, these companies are leveraging their research to create products such as QSFP modules or tunable transceivers that are selling today. So even though you could make these transceivers tiny, they package them in standard form factors in order to develop a revenue stream in hopes that the technology can truly be used for miniature devices in the near future. Pretty smart business plan I think – especially since we’ve already seen a glimpse of the miniaturization products with Avago’s MicroPOD, Intel’s Light Peak and Luxtera’s OptoPhy, which can also be considered optical engines. And, which are supposedly on the cusp of true adoption into active equipment.

 

Luxtera’s Contribution to a Push for All-Optical Networks

Yesterday I wrote about Avago’s new miniaturized transmitters and receivers so today I’d like to introduce you to a similar product from Luxtera. Well known for its CMOS photonics technology, Luxtera actually introduced its OptoPHY transceivers first – in late 2009.

Luxtera took a different approach to its new high-density, optical interconnect solution. It is a transceiver module and is based on LW (1490nm) optics. Just like Avago’s devices, the transceivers use 12-fiber ribbon cables provided by Luxtera, but that’s really were the similarities end. The entire 10G–per-lane module only uses about 800mW compared to Avago's 3W, and they are true transceivers as opposed to separate transmitters and receivers. Luxtera is shipping its device to customers, but have not announced which ones yet.

In addition to the projected low cost for these devices, what should also be noted is that all of the solutions mentioned in the last three entries – Intel’s Light Peak; Avago’s MicroPOD and Luxtera’s OptoPHY – have moved away from the pluggable module product theme to board-mounted devices. This in and of itself may not seem significant until you think about why there were pluggable products to begin with. The original intent was to give OEMs and end users flexibility in design so they could use an electrical, SW optical or LW optical device in a port depending on what length of cable needed to be supported. You could also grow as you needed to – so only populate those ports required at the time of installation and add others when necessary. The need for this flexibility has seemed to have waned in recent years in favor of density, lower cost and lower power consumption. The majority of pluggable ports are now optical ones, so why not just move back to board-mounted products that can achieve the miniaturization, price points and lower power consumption?