A supercomputer small enough to fit inside a laptop PC and draw no more power than a light bulb: that's the promise IBM makes in light of a new milestone its researchers have reached in the area of silicon photonics. This milestone involves a new silicon Mach-Zehnder electro-optic modulator—a device designed to convert electric signals to light pulses in a silicon chip—which Big Blue says is 100 to 1,000 times smaller than previously demonstrated modulators of the same type.
The company describes the modulator as follows, with a helpful video to illustrate things:
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 is delivered to the optical modulator, which acts as a very fast "shutter" which controls whether the input laser is blocked or transmitted to the output waveguide. When a digital electrical pulse arrives from a computer core to the modulator, a short pulse of light is allowed to pass 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.
According to IBM, the new, smaller modulator paves the way for "complete optical routing networks to be integrated onto a single chip." Big Blue predicts networks of "hundreds or thousands of cores" packed together inside a single chip, in which optical interconnects could offer a 100-fold speed increase over wires while using 10 times less power.