Increasing a processor's performance has never been a simple challenge. Advances developed in obedience to Moore's Law allowed us to enjoy very fast platforms, but the future of computing will demand even more advanced ideas, especially if we want to reduce energy consumption. One of those ideas is silicon photonics technology, which IBM has been working on for a long time and successfully evaluated this week.
Many believe the silicon era is coming to an end, but it may be necessary to talk about silicon accompanied by traditional conductors like copper. The problem is that we need to move data. Lots of data. Engineers around the globe have created all sorts of methods to pack more bytes into the same channel, yet this is not magic, and there are definite limits. The solution these engineers seek to implement is nothing less than optics. We are well aware of the virtues of fibers, from greater available bandwidth to reduced energy consumption. But connecting two data centers with fiber is one thing; bringing that same technology inside chips is another. In other words, it's time for the long friendship between optics and electronics to become a marriage, giving rise to the long-awaited electro-optical chip, which will replace part of the electrical signals with light pulses.
Reaching 100 Gbps and Beyond
That is exactly what IBM's people managed to evaluate in recent days. It is estimated that its brand-new silicon photonic chip will soon enable the development of new transceivers with a maximum speed of 100 gigabits per second, thanks to four multiplexed channels of 25 gigabits per second each. Although the optics and electronics of the chip share the same package, there are still certain differences in scale, and the lasers are produced "outside" the chip, requiring dedicated input ports in turn. Even so, the theory behind this technology is truly impressive. The fact that the chip has four channels today does not mean it is a definitive barrier. IBM believes it is possible to manufacture an electro-optical chip with a performance of 800 gigabits per second.
The Demo and Next Steps
In the chip demo IBM conducted, an interconnection at 100 Gb/s was established with a maximum distance of two kilometers. Those numbers might not seem so interesting if we consider that Ethernet standards for 40 and 100 gigabits already exist, but the best is yet to come. IBM's next step is to place laser generation "inside" the package (likely with III-V semiconductors), and later, to have the entire optical system on par with transistors on the same die. Until then, patience...
