Engineers make leap in optical networks

A team of Stanford University electrical engineers has discovered how to switch a beam of laser light on and off up to 100 billion times a second with materials that are widely used in the semiconductor industry.

The group used a standard chipmaking process to design a central component of optical networking gear that is potentially more than 10 times as fast as the highest-performance commercial products available today.

The team reported its discovery in the current issue of the magazine Nature and announced it Wednesday. Such an advance could accelerate the decline in the cost of optical networking and transform computers by making it possible to interconnect computer chips at extremely high data rates.

The communications industry now uses costly equipment to transmit data over optical fibers at up to 10 billion bits a second. Researchers, however, are already experimenting with optically linked computers in which components may be located on different sides of the globe. Cheap optical switches would also make it possible to create data superhighways inside computers and reorganize them for better performance.

"The vision here is that, with the much stronger physics, we can imagine large numbers--hundreds or even thousands--of optical connections off of chips," said David Miller, director of the Solid State and Photonics Laboratory at Stanford University. "Those large numbers could get rid of the bottlenecks of wiring, bottlenecks that are quite evident today and are one of the reasons the clock speeds on your desktop computer have not really been going up much in recent years."

The device reported by the team, called a modulator or solid-state shutter, could also have a powerful effect on the telecommunications industry, which is already being transformed by the falling cost of optical fiber networks.

Constructed from silicon and germanium, the device alternately blocks and transmits light from a separate continuous-wave laser beam, making it possible to split the beam into a stream of ones and zeros.

The effect, known as a quantum-confined Stark effect, had been demonstrated before but had not been expected in germanium, a material that is

compatible with the industry's silicon-based manufacturing technologies.

"What we achieved is somewhat surprising," said James Harris, a Stanford University electrical-engineering professor who is a member of the research group. "No one thought it would work."

The research project was supported by Intel and the Defense Advanced Research Projects Agency (DARPA) at the Pentagon. Intel has been intensely interested in producing optical communications components with standard chipmaking tools, for both networking and computer communications applications. Ted Kamins, a quantum materials specialist at Hewlett-Packard Laboratories, also contributed to the research effort.

"They've made a big leap," said Mario Paniccia, director of the Intel Photonics Technology Laboratory. He acknowledged, however, that there is a significant gap between research results and commercial availability of devices based on those results.

Several industry executives said the advance is significant because it means that optical data networks are now on the same Moore's Law curve of increasing performance and falling cost that has driven the computer industry for the last four decades.

In 1965, Intel's co-founder, Gordon Moore, noted that the number of transistors that could be placed on a silicon chip was doubling at regular intervals. The semiconductor industry has held to that rate of change since then, giving rise to the modern era of microelectronics that has transformed the global economy.

Now that rate of change could be directing the future of the telecommunications industry. Computer and communications industry executives say they believe that advancements in inexpensive optical networks will transform the computer industry and other major industries as diverse as the financial marketplace and Hollywood.