IMAGE: DIGITAL VISION/MAGICTORCH; PHOTO MANIPULATION: JOHN MACNEILL

For years we've been hearing about all the fantastic things computers will be able to do once they process data with light instead of electricity. The mysteries of the universe will be unlocked. A golden age of limitless computing power and bandwidth will usher in a techno-utopia.Don't believe the hype.

Setting aside the question of whether an all-optical processor would even be desirable, optical computing schemes lack the photonic equivalent of the most fundamental computing element, the transistor. That device—first demonstrated in 1947, when John Bardeen and Walter H. Brattain stuck two cat-whisker wires onto a germanium base and showed power gain from one wire, called the emitter, to the other, called the collector—spawned the US $300-billion-per-year semiconductor industry. The transistor makes possible our digital lifestyle: cellphones and PCs, digital cameras and MP3 players, medical imaging systems and set-top boxes, supercomputers and the Internet, and more.

The transistor has given us much during the last six decades. Now it has given us light, and with that, the potential for much speedier broadband communications in both telecommunications networks and within and between chips—not in some remote sci-fi future, but perhaps within the next decade.

Our team at the University of Illinois at Urbana-Champaign, has at its disposal an extraordinary prototype transistor that can switch on and off more than 700 billion times per second, faster than any other transistor in the world. On a hunch two years ago, we inspected in greater depth some samples of this transistor, which are made from indium phosphide and indium-gallium-arsenide, the same sort of semiconductor compounds used in today's light-emitting diodes and laser diodes.

We detected significant light in the base of these transistors and immediately began to engineer a new, more powerful kind of device, a transistor laser. Our transistor puts out both electrical signals and a laser beam, which can be directly modulated to send optical signals at the rate of 10 billion bits per second. With some further modification, the transistor laser will eventually send a staggering 100 billion bits per second or more. And it will likely do so at room temperature.