Can IBM connect cores in a chip with light?
IBM has come up with a technology that could one day let different cores on a processor exchange signals with pulses of light, rather than electrons, a change that could lead to faster and far more energy efficient chips.
The device, known as a silicon Mach-Zehnder electro-optic modulator--converts electrical signals into pulses of light. The trick is that IBM's modulator is 100 or more times smaller than other small modulators produced by other labs. Eventually, IBM hopes the modulator could be integrated into chips.
Electrons in, photons out.
(Credit: IBM)Here's how it works. Electric pulses, the yellow dots, hit the modulator, which is also being hit with a constant beam of light from a laser. The modulator emits light pulses to correspond to the electrical pulses. In a sense, the modulator is substituting photons for electrons.
Since the beginning of the decade, several companies--Intel, Primarion, Luxtera, IBM--have been coming up with components that, ideally, will let chip designers replace wires in computers and ultimately chips with optical fiber. Wires radiate heat, a big problem, and the signals don't travel as fast as light pulses. (The research in this area is known as silicon photonics and optoelectronics.)
The problem with optical technology, however, is making it small. Optical components historically have been tricky to produce and tend to be fairly large. Computer makers need components that measure only a few millimeters on a side. The idea is to come up with a way to produce modulators, lasers, waveguides and other devices on silicon manufacturing lines.
Right now, it remains an open question when these products will come to market. Still, the plethora of prototypes is a strong indication that progress is moving along well.
The hard part has always been getting silicon to lase. There have been detectors and modulators around for a long time. However, there has been some good progress lately in designing lasers compatible with VLSI mass production methods, so the promise of inter-chip and intra-chip communication via light may finally come to be.