IBM, which for years told its mainframe users not to consider optical disk drives because they were not sufficiently reliable, now does seem to think they may be all right after all. The company’s Almaden Research Center in San Jose, California says it has developed a compact, efficient and potentially practical source of blue laser light with output power and optical properties attractive to a wide range of applications. It has been something of a Holy Grail in laser optics, IBM says, because it could lead to optical data storage devices operating at about four times present storage densities or play an integral part in other applications such as colour displays and chemical analysis. The new laser device is entirely solid state, which usually results in more compact and reliable lasers than those requiring gases or liquid dyes. Its key features are a 10% efficiency in converting electricity into blue light – at least five times more efficient than previous devices – and its ability to produce stable, low-noise output that can be focused to diffraction-limited spots. Blue light can be focused to 0.4 microns against 0.8 microns for the infra-red lasers currently used. The IBM technique is to use frequency doubling to convert infra-red light from a diode into blue light, passing it through a Potassium Niobate crystal that doubles the frequency of a narrow colour range of light passing through it. No indication of when it might be available for products.
