Talking with light, within the chipSunday, March 4th, 2012 by Roberto Saracco
Moore’s law has turned the world upside down, technologically but also from and economic and perceptual standpoint. We take evolution for granted, we “know” that the television or digital camera we just bought will be obsolete in a few years and we will buy a better one at a lower price.
The magic of Moore’s law takes place within the chip. It is the production process that creates more densely packed chips, hence more feature rich and less expensive. But if you need two chips to do what you want to do, the cost of putting the two chips together is not coming down, actually it is slightly increasing (robots are at work here, and they are expensive so their cost can only be counterbalanced by massive production volumes).
Hence, it is good to know that researchers are finding ways to embed within a chip more and more. And this is what this news, coming from MIT, is all about.
Another reason to look for an optical solution is energy. Sending electrons is quite more expensive than sending photons. According to the Japanese ministry of Economy if nothing changes at the technological level the Information Technology deployed in Japan will use 250 TWh of energy per year in 2025, over ten times more than the present energy use estimate in IT.
Setting up optical communications through servers adds to the overall cost and optical communications within multiple chip core is simply not feasible. That is, till now.
The announcement from MIT shows that monolithic integration (placing on the same chip the optical and electrical part) is becoming feasible and, moreover, it is expected to become also cheaper.
The big challenge, though, is to be able to use existing chip production plants to support monolithic integration. So far, the focus of manufacturing has been on packaging more and more in the chip, whilst the embedding of laser and optoelectronic detectors would reverse the drive.
The production is really the crucial factor for success. Chip manufacturing has obtained such a sophistication that any divergence from the main stream is bound to disrupt its economics. Hence the resistance from manufacturers. However, the pressure put by the growing energy challenge may lead them to reconsider and start redesigning chips from scratch.
Having chip talking through photons can have a boosting effect on the economics of optical fibers whose termination points, today, add to the cost of the swap from copper to fibre.