RALEIGH, N.C., Dec. 12 -- Corning Inc. will spend $450 million to expand its Cabarrus County fiber optic cable plant in Concord, N.C., generating 475 new jobs and making it the largest such facility in the world, said Corning. The announcement comes on the heels of a $550-million addition earlier this year. The increased capacity in these plants is allowing us to keep pace with growing worldwide demand for optic fiber, said Corning division vice president Tom Nettleman.The company will increase production of fiber optic cable by 25 percent a year through 2004. Corning's division in North Carolina will eventually receive investments totaling $2.5 billion and employ more than 6500 people by 2004, the company said.