Blue-violet laser diodes will effectively disappear from the US if Cree Inc. and North Carolina State University prevail in a lawsuit against Nichia Corp. and its US subsidiary. Cree and the university filed suit against Nichia of Anan, Japan, and its US subsidiary in September, alleging that importing and selling Nichia's gallium-nitride-based laser diodes infringes on a US patent. The lawsuit asks the court to prevent Nichia and its US distributor, Ni-chia America Corp. of Mountville, Pa., from selling the lasers in the US. Nichia officials told US customers they are confident that they will prevail in the litigation and will continue to supply laser diodes to US firms. Seeing Purple Nichia has been the only commercial supplier of blue-violet semiconductor lasers since its lasers began to appear at photonics exhibitions in 1999. This means an injunction against selling the Nichia devices would frustrate US companies that have developed OEM modules and end products based on the violet laser. "Should Nichia be barred from marketing the diode in the US, it will be a great inconvenience for Power Technology and our customers," said Walter Burgess, marketing manager for Power Technology Inc. of Little Rock, Ark. "Our customers have commenced integration of the blue lasers into their OEM applications." Burgess and Dave Clark of Coherent Inc. in Santa Clara, Calif., said they have seen no reduction in violet laser diode availability. "In fact," Burgess said, "we can get blue laser diodes faster than we can get some red and IR laser diodes." The US lawsuit follows three in Japan, where Nichia sued one of Cree's distributors, Sumitomo Corp. The Japanese lawsuits, filed in December 1999 and April 2000, allege that Cree's LEDs infringe on two of Nichia's Japanese patents. Cree's lawsuit refers to North Carolina State University's US Patent No. 6,051,849, which was filed in February 1998, granted in April 2000 and licensed to Cree. It covers gallium-nitride semiconductor structures and their manufacture, including a lateral epitaxial overgrowth technique. This technique is at the heart of Cree's lawsuit, but even a technical description belies the difficulty of producing commercially viable GaN laser diodes. The problem is attaining useful laser lifetime and reliability. Cree joins Sony Shiroshi Semiconductor Inc. and Xerox Palo Alto Research Center among the major commercial firms that are struggling to match Nichia's device lifetime specifications. None has yet announced even a laboratory demonstration of a commercially acceptable lifetime figure, but as we went to press, Cree announced a laboratory demonstration of 100-hour lifetime at 1 to 3 mW.