Moving Toward a Tera-Scale Computer

Researchers at Intel have found a way to boost the speed of a silicon modulator so that it can encode data onto beams of light at a rate of 40 gigabits per second, besting the company’s previous record by 10 gigabits. By comparison, commercial modulators, which are made of expensive, nonsilicon materials, have only recently been available at 40 gigabits per second.

Modulators are crucial components in all fiber-optic networks, converting bits of information into pulses of light. But today’s modulators are made of expensive materials such as lithium niobate, and they can’t be easily shrunk down and mass-produced. Mario Paniccia, the lead researcher on the work, believes that by making modulators and other photonic devices, such as lasers and detectors, out of cheap silicon, he can revolutionize telecom, as well as the inside of your computer. If photonic devices are cheap, he says, then they could be integrated into the guts of a PC; speedy beams of light could replace the copper wires currently used to move bits around between processing cores and to and from the memory.

Intel has been on a roll recently, churning out journal articles and conference papers detailing its silicon photonic devices. In 2004, Paniccia’s team unveiled a one-gigabit-per-second silicon modulator, and in 2005, the researchers improved the speed to 10 gigabits. That same year, they built a remarkably good all-silicon laser. In 2006, the team announced a “hybrid laser” that combines indium phosphide with silicon, allowing it to be processed similarly to other silicon devices. (The hybrid laser will most likely be used in communication and computer applications, while the all-silicon laser will be useful for certain types of medical imaging.) And in January, the researchers bumped up their modulator to 30 gigabits per second.

With all these devices quickly improving in performance, Paniccia says that it’s time to start thinking about integrating hybrid lasers and modulators onto a single chip. Since both devices are based in silicon, they can be made cheaply, taking advantage of existing fabrication facilities and techniques. Ideally, within five years, says Paniccia, Intel will have a chip the size of a fingernail that can send a terabit’s worth of data. That would be enough speed to download DVD-sized movies from the Internet in seconds and render complex three-dimensional graphics on computers in real time.