Corning Inc. of Corning, N.Y., has revised its plans to expand its fiber manufacturing capability, citing the market slump. The company will delay the construction of a facility in Oklahoma City by 12 to 18 months, pushing initial production to 2004 or 2005. Expansion of the Concord, N.C., plant has been moved to the first half of next year. Alan Eusden, senior vice president at Corning, said that the company is committed to the planned Oklahoma City facility, and that it expects the demand for bandwidth -- and fiber -- will soon recover.