What bottleneck? Silicon photonics technology boosts interconnect speeds


INTEL has publicly demonstrated a fully functional silicon photonics module operating at 100 Gb/s.

The Intel Silicon Photonics Technology is a completely integrated module which includes silicon modulators, detectors, waveguides and circuitry.

Intel believes this is the only module in the world that uses a hybrid silicon laser. The technology was demonstrated during a keynote at the Intel Developer Forum in Beijing.

Earlier this year, Intel’s CTO Justin Rattner engaged Sun Microsystems co-founder Andy Bechtolsheim in a discussion about the technology.

According to Bechtolsheim, copper-based technology limits the speed and reach of links to around 5m, and this has become a looming problem in the technology industry. While speeding optics-based systems are available, they are very expensive, limiting their use to select high-end systems.

“What has been missing is the technology that allows the speedy link to get out of the box into other boxes,” he said. “It comes down to speed, power consumption, and the cost. Intel Photonics Technology is the first we’ve seen which has all three attributes to enable taking PCI connectivity out of the box.”

The problem was an industry-wide conundrum, since processors have managed to more-or-less keep up with Moore’s Law, but development in interconnect technology was limited.

“There was a risk that if the interconnect technology did not keep up with Moore’s Law, that the interconnect would become the limiting factor in these cloud/distributed computing installations,” Bechtolsheim explained.

“This technology will change the tide, by allowing a very high bandwidth interconnect, not just within the rack, but across a whole range of racks in the centre.”

As a universal transfer layer between servers and racks, Bechtolsheim says it is as important a development as PCI-Express.

“With this kind of technology from Intel, 100 Gbit/s speeds has become a very viable technology for the networking industry, and it will take off as soon as it ships.”

According to Rattner, Intel has spent a decade in its efforts to create its photonic technology.

“In the last few years, we have taken all we’ve learned in research and taking it in to the factory to prove we can build the technology in high volumes, with high yields,” he said.

Unlike optics-based systems, many of which are hand-assembled with low yield, Intel boosted the affordability of its photonic systems by building it via a silicon process.

“We have been developing process technology to create a monolithic, photonic sub-system. We build these just like you build any other kind of IC, in a standard chip factory,” Rattner explained.

“We also figured out how to test them, like IC testing. We can test them while they are still at the wafer level, both electrically and optically. When we can complete that test, we know which die are good and which are bad, which help further reduce our cost.”

Intel anticipates further developing on the photonic technology, with a formidable patent library around the technology which will allow it to build a business around the technology.

“We see the inherent scalability of the technology. We’re not even close to the single lambda speeds that is described in the literature. We can make the photons go faster, put more stuff on the fibre, etc,” Rattner said. “We think it will be a very powerful and versatile technology.”