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Nanowires Produce Ultraviolet Laser Light At Room Temperature
CELIA HENRY
A team of scientists at the University of California, Berkeley, and Lawrence Berkeley National Laboratory (LBNL) has developed nanowires that can be used as ultraviolet lasers [Science, 292, 1897 (2001)].
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MICROGRAPHS Arrays of zinc oxide nanowires are patterned on a gold-coated sapphire surface. Each of the squares (top) contains many individual nanowires (bottom). |
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Team leader Peidong Yang, an assistant professor at UC Berkeley and a faculty scientist at LBNL, says this is the first demonstration of using nanowires to make an active lasing device. He believes that such lasers could find use in applications such as information storage and microanalysis; for example, lab-on-a-chip devices.
Yang and his coworkers grew single-crystal zinc oxide nanowires 20 to 150 nm wide and 2 to 10 µm long on gold-coated sapphire substrates. The wires grow--catalyzed by the gold--vertically from the substrate.
The nanowires form a natural resonance cavity suitable for lasing--without the addition of fabricated mirrors. Instead, the wires provide their own mirrors, with the interface between the substrate and ZnO serving as one mirror and the perfectly cleaved hexagonal end of the nanowire serving as the other.
Above a lasing threshold, when the wires are excited with 266-nm light, they lase in different modes between 370 and 400 nm. Although the team demonstrated collective lasing from the arrays, Yang says the wires will also lase individually.
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