Furukawa Gets Raman Patent

TOKYO -- Furukawa Electric Co., Ltd. announced that the United States Patent and Trademark Office issued a patent covering techniques developed by Furukawa Electric that improve the use of Raman amplifiers for wavelength division multiplexing transmission systems. The patent covers a novel technique called 'wavelength division multiplexed pumping,' in which multiple wavelengths are simultaneously used to achieve the desirable shape of Raman gain spectrum for WDM transmissions. This invention enables a reliable laser diode to be used for Raman amplifiers. The Company expects the techniques disclosed in this patent to be used in many next-generation WDM systems, key elements in the development of future high-speed optical transmission systems. The patent, therefore, is expected to be a crucial part of the development of Furukawa's global strategy as a leading provider of components for optical communications. Most current optical communication systems use optical amplifiers together with WDM transmission technologies in order to reduce cost by efficiently multiplexing signals and extending the distance of non-electrically regenerated transmissions. Raman amplifiers, a type of optical amplifier, utilize conventional optical transmission fiber for gain medium, while Erbium-doped fiber amplifiers (EDFA), widely used in conventional WDM transmission systems, use Erbium-doped fiber for gain medium. Since they can work as distributed amplifiers, Raman amplifiers have the advantage of having lower noise than EDFA. Most next-generation WDM systems will employ both EDFA and Raman amplifiers together with deployed optical fibers. Fundamental patents for Raman amplifiers have already expired since most basic research on Raman amplifiers was carried out in the 1970s. In the 1980s, there were also extensive studies on Raman amplifiers; however, until now, there has been no need to study the applications for Raman amplifiers in WDM transmissions.

Furukawa Electric Co. Ltd.