WILMINGTON, Del., Feb 15 -- Sumitomo Electric Industries Ltd. is suing Furukawa Electric Co Ltd., for selling a product that Sumitomo alleges infringes its patent. In papers filed in the US District Court in Delaware, Sumitomo alleged that Furukawa's Rainbow Pump for increasing the data-carrying capacity of communications networks infringes Sumitomo's 1998 patent for a "Semiconductor laser module and optical fiber amplifier."
    Last year Furukawa said in a letter to Sumitomo that it considered the Sumitomo patent to be invalid, court papers say. Meetings between the two companies since then have failed to resolve the dispute. Both companies are based in Japan, but Furukawa sells its products through two US units named in the lawsuit, Fitel Technologies Inc. and Furukawa Electric North America Inc., of New Jersey and California respectively.