Light chips find a place to take root.Light-based microcircuits could process more information and do it more quickly than electronic ones, theorists predict. They also would run much cooler and free of electromagnetic interference See EMI. . However, there's no material suitable for chips using photons that's equivalent to semiconductors using electrons. By taking cues from a natural material--the opal--researchers in Canada and Spain have come up with a possible feedstock for light chips (SN: 8/7/99, p. 87). While cheap and easy to mass-produce, this new crystal refuses to pass or absorb light in the 1.5-micrometer wavelength range favored for fiber-optic communications. That gap in permitted wavelengths enables designers to create optical components such as laser cavities, waveguides, and optical transistors in the material, says Sajeev John Sajeev John is a University Professor at the University of Toronto and Government of Canada Research Chair holder. He received his Bachelors degree in physics in 1979 from the Massachusetts Institute of Technology and his Ph.D. in physics at Harvard University in 1984. His Ph.D. of the University of Toronto Research at the University of Toronto has been responsible for the world's first electronic heart pacemaker, artificial larynx, single-lung transplant, nerve transplant, artificial pancreas, chemical laser, G-suit, the first practical electron microscope, the first cloning of T-cells, . Carving holes, lines, or other features into the crystal would selectively let light in and control its behavior. In the May 25 NATURE, the researchers report growing glass balls--870 nanometers in diameter--in solution and then carefully sedimenting them to stack with military precision. After sintering sintering, process of forming objects from a metal powder by heating the powder at a temperature below its melting point. In the production of small metal objects it is often not practical to cast them. the balls together, the team filled the interstices with silicon. Acid then etched away the glass-ball template, which has a structure resembling an opal's, leaving a crystal of silicon shells. Such material has been the "holy grail" of photonic crystal A nanostructured array of holes used as an optical semiconductor. Just as electronic bandgaps prevent electrons from passing through, photonic crystals create photonic bandgaps that confine light. research, John says. It is "a very important development," agrees Eli Yablonovitch of the University of California, Los Angeles UCLA comprises the College of Letters and Science (the primary undergraduate college), seven professional schools, and five professional Health Science schools. Since 2001, UCLA has enrolled over 33,000 total students, and that number is steadily rising. . For lasers and other active components, he suggests, photonic crystals of other substances, such as gallium arsenide, may prove better. |
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