An important trend in the microelectronics industry is to increase the parallelism in computation by multi-threading, by building large scale multi-chip systems and, more recently, by increasing the number of cores on a single chip. For example, the IBM Cell processor which powers Sony's PlayStation 3 gaming console consists of nine 'brains', or cores, on a single chip. As users continue to demand greater computing performance, chip designers plan to increase this number to tens or even hundreds of cores.
This approach, however, only makes sense if each core can receive and transmit large messages from all other cores on the chip simultaneously. The individual cores located on today's multi-core microprocessors communicate with one another over millions of tiny copper wires. However, this copper wiring would simply use up too much power and be incapable of transmitting the enormous amount of information required to enable massively multi-core processors.
IBM researchers are exploring an alternative solution to this problem by connecting cores using pulses of light in an on-chip optical network based on silicon nanophotonic integrated circuits. Like a long-haul fibre-optic network, such an extremely miniature on-chip network will transmit, receive and route messages between individual cores that are encoded as a pulses of light. It is envisioned that using light instead of wires, as much as 100 times more information can be sent between cores, while using 10 times less power and consequently generating less heat.