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.
Most machine design engineers will survey existing component manufacturers for standard linear guide products, limiting what they can do with their designs. Using extruded aluminum profile guides can customize machine designs while shrinking the bill of materials.
Practically all electronic devices today contain metals that may
be coming from conflict-ravaged African countries. And political pressures will increasingly influence how these minerals are sourced and used in products.
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