IDF Fall 2006 – Tera-scale

As the Intel Developer Forum kicks off in San Francisco, Riyad takes a look at Intel's vision of Tera.

But it’s the third area of Tera-scale that’s the most challenging – how can you improve the speeds of I/O exponentially using current interconnect technology? The answer is that you can’t. The solution is something that Intel touched on a year ago, when it announced the first silicon based Raman laser – optical switching. The problem with the laser that Intel showed a year ago was that it still needed an external optical pump, which kind of defeated the purpose. But Intel has obviously been beavering away in this area, because now it has a hybrid silicon laser using an electronic pump.

The hybrid silicon laser is the result of a collaboration between Intel and the University of California at Santa Barbara (UCSB). It’s called a hybrid laser because it combines the light emitting properties of indium phosphide with the already established light routing properties and manufacturing flexibility of silicon.

The silicon is manufactured to create a waveguide for the laser, then a layer of indium phosphide is bonded to the silicon. As the indium phosphide emits light, it travels down the silicon waveguide, carrying data with it.

Justin Rattner (CTO Intel Corp.) gave the World’s first public demonstration of a hybrid silicon laser in operation. The demonstration showed four hybrid lasers producing optical interconnects, and Rattner also showed that the connections were lost if he waved his hotel room key in front of the laser. It seems that integrated optical switching is a reality.



Multiple hybrid lasers can be implemented into a single die, then the signals are multiplexed and sent out through a single fibre optic link. At the other end the signal will be separated once more and all the streams interpreted individually.

Using photonic techniques like this will allow the third piece of the Tera-scale puzzle to fall into place, and provide I/O speeds in excess of one Terabit per second. It’s also worth noting that using optic switching instead of traditional copper interconnects will reduce heat considerably and help continue Intel’s drive towards a better performance per watt ratio.

It’s unlikely that we’ll see this kind of technology in the mainstream for some time, but it does go to show how far ahead Intel is thinking.

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