ALLENTOWN, Pa., August 15 -- Agere Systems has announced it will cut a third of its work force -- about 4,000 jobs -- and exit its optoelectronics business, which represented about 10 percent of its total revenues. Instead, it will focus on its main revenue generator, supplying integrated circuits that access, move and store network information for everything from telecommunications hardware to desktop computers, said John Dickson, president and CEO. Agere is seeking a buyer for all or parts of this business, but will discontinue optoelectronics operations no later than June 30, 2003. The company said it plans to cut its work force from 11,200 to 7,200 by the end of 2003, close a number of factories, and consolidate its US manufacturing in Orlando, Fla. Agere said it would close or sell facilities in Dallas, Texas; Alhambra and Irwindale, Calif.; and Matamoros, Mexico. Agere said it expects to move its Allentown, Penn., manufacturing operations to Orlando by the end of September.