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  • Nichia Chemical Violet Laser Boosts DVD Storage Capacity
  • January 20, 1999 (TOKYO) — Nichia Chemical Industries Ltd. said that next month it will ship a violet laser diode with a gallium-nitride (GaN)-based semiconductor that can boost DVD storage.
    The laser has a wavelength of 400 nanometers.

    Blue-violet lasers are a critical component in demand by leading audio visual equipment makers, an engineer at an AV maker said.

    Nichia Chemical, Japan’s leading manufacturer of phosphors for CRTs and lamps, was also successful earlier in developing blue light emitting diodes (LEDs).

    The violet laser to be sampled by the company in February allows an increase of about 2.5 times in the data storage capacity of current DVDs.

    This should will realize new media such as DVDs that can record motion pictures with a high quality equivalent to that of high-definition television (HDTV) and video disk recorders (VDR) that will kick video tape recorders (VTR) out of the market.

    Companies including Sony Corp., Pioneer Electronic Corp. and Matsushita Electric Industrial Co., Ltd. are competing head-to-head in developing prototypes or proposing standards for those devices, which are considered to be the next-generation AV products that are strategically important in the digital HDTV broadcast era.

    The new violet laser has a wavelength of 400nm and output power of 5mW. Its threshold current is about 40mA. Its operating current at 5mW output is 50mA, and its operating voltage is approximately 5V. It has 10,000 hours of operating life with continuous operation at room temperature.

    Nichia Chemical said the 400nm wavelength can give the company the highest yield in its production process. Optical disk equipment makers also are expressing their approval for that wavelength, company officials said.

    The data storage density of optical disks increases with shortened wavelengths. Some optical disk equipment makers are concerned about that wavelength because it is too short.

    Polycarbonate, which is a base material used for DVD devices, drastically decreases its transmittance with a wavelength of 390nm and shorter. The wavelength of 400nm only has a margin of 10nm, which means the equipment design will be difficult if fluctuations of ambient temperature and aging factors for components are taken into consideration.

    However, Nichia Chemical has no plan to change that wavelength at present. And therefore, standards for high-density DVD devices will be firmed up on a premise that the wavelength is 400nm.

    Related story: Blue-Violet Laser to Debut in ’98 for Post-VTR Products

    (Nikkei Electronics)



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