Computer designers have long fantasized about using light rather than electrons to move data between microprocessors. Such optical interconnects would overcome the bandwidth bottleneck inherent in the wires and take full advantage of the leaps in processor speed. But combining two very different technologies—electronics and photonics—in the same silicon chip has been a high hurdle to overcome.
Now a group of researchers has come up with a way to build huge numbers of silicon transistors and optical components on the same chip, doing so for the first time, without a major overhaul of the chipmaking process. And they used it to build an IC containing 70 million transistors and 850 photonic components, which together provide all the logic, memory, and interconnection functions a processor needs.