The goal: push network speeds 10 to 1,000 times higher. The method: use semiconductor diode lasers that transmit information on tens to hundreds of different wavelength channels simultaneously through the same optical fiber. UC Berkeley Electrical Engineering Professor Constance Chang-Hasnaina hopes to push the network speeds beyond the gigabit rate by etching a microscopic, tunable laser directly on a computer chip. "Tunable lasers are available today, but they are about 100 million times larger and a million times slower than this," Chang-Hasnain says. "An integrated device that includes the laser and associated electronics would fit on the same chip and be significantly cheaper." Chang-Hasnain and colleagues etched a vertical cavity surface-emitting laser (VCSEL) directly onto a gallium arsenide chip using techniques commonly employed to make integrated circuits and microprocessors. Each laser measures only 150 by 200 microns. The professor suggested that such lasers could also be used for wavelength division multiplexed systems. This would speed communication between processors in a computer made up of many parallel processors, eliminating connections to a motherboard. FAX: (510) 643-7461.
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