Time Lens Speeds Optical Data
By Katherine Bourzac on September 28, 2009
Researchers at Cornell University have developed a simple silicon device for speeding up optical data. The device incorporates a silicon chip called a "time lens," lengths of optical fiber, and a laser. It splits up a data stream encoded at 10 gigabits per second, puts it back together, and outputs the same data at 270 gigabits per second. Speeding up optical data transmission usually requires a lot of energy and bulky, expensive optics. The new system is energy efficient and is integrated on a compact silicon chip. It could be used to move vast quantities of data at fast speeds over the Internet or on optical chips inside computers.
Most of today's telecommunications data is encoded at a rate of 10 gigabits per second. As engineers have tried to expand to greater bandwidths, they've come up against a problem. "As you get to very high data rates, there are no easy ways of encoding the data," says Alexander Gaeta, professor of applied and engineering physics at Cornell University, who developed the silicon device with Michal Lipson, associate professor of electrical and computer engineering.
The new device could also be a critical step in the development of practical optical chips. As electronics speed up, "power consumption is becoming a more constraining issue, especially at the chip level," says Keren Bergman, professor of electrical engineering at Columbia University, who was not involved with the research. "You can't have your laptop run faster without it getting hotter" and consuming more energy, says Bergman. Electronics have an upper limit of about 100 gigahertz. Optical chips could make computers run faster without generating waste heat, but because of the nature of light--photons don't like to interact--it takes a lot of energy to create speedy optical signals.
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