IBM researchers reached a significant milestone in the quest to send information between the "brains" on a chip using pulses of light through silicon instead of electrical signals on copper wires. The breakthrough -- a significant advancement in the field of "Silicon Nanophotonics" -- uses pulses of light rather than electrical wires to transmit information between different processors on a single chip, significantly reducing cost, energy and heat while increasing communications bandwidth between the cores more than a hundred times over wired chips. The new technology aims to enable a power-efficient method to connect hundreds or thousands of cores together on a tiny chip by eliminating the wires required to connect them. Using light instead of wires to send information between the cores can be as much as 100 times faster and use 10 times less power than wires, potentially allowing hundreds of cores to be connected together on a single chip, transforming today's large supercomputers into tomorrow's tiny chips while consuming significantly less power.
IBM's optical modulator performs the function of converting a digital electrical signal carried on a wire, into a series of light pulses, carried on a silicon nanophotonic waveguide. First, an input laser beam (marked by red color) is delivered to the optical modulator. The optical modulator (black box with IBM logo) is basically a very fast "shutter" which controls whether the input laser is blocked or transmitted to the output waveguide. When a digital electrical pulse (a "1" bit marked by yellow) arrives from the left at the modulator, a short pulse of light is allowed to pass through at the optical output on the right. When there is no electrical pulse at the modulator (a "0" bit), the modulator blocks light from passing through at the optical output. In this way, the device "modulates" the intensity of the input laser beam, and the modulator converts a stream of digital bits ("1"s and "0"s) from electrical signals into light pulses. December 05, 2007