A small laser could be the key to increasing the amount of data storage on compact disks if Peidong Yang, a professor of chemistry at the University of California in Berkeley, has his way. His laser, which is one thousand times thinner than a human hair, is also said to be an alternative to today’s solid state lasers made from gallium arsenide and gallium nitride. Instead, Yang uses zinc oxide. He paints a gold catalyst onto a sapphire and places it in zinc oxide. The gold forms the crystal wires, which are hexagonal in cross section. The arrays of wire resemble hairbrush bristles. They emit UV light from their flat tips, which act like mirrors. The ends attached to the semiconductor also act like mirrors. Light emitted by the zinc oxide bounces back and forth, causing emission and amplification of the light. Yang uses optical pumping for exciting the zinc-oxide molecules. “Optical pumping uses a conventional laser for exciting our nanowire sample, so that stimulated emission can be generated from the nanowires,” explains Yang. “One of the next steps in commercializing the nanolaser is its successful integration as a miniaturized light source in optoelectronic applications,” he says. For more information, contact Yang at (510) 643-1545 or go to www.cchem.berkeley.edu.
Independent science safety company Underwriters Laboratories is providing new guidance for manufacturers about how to follow the latest IEC standards for implementing safety features in programmable logic controllers.
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