SAN JOSE, Calif., March 18 -- New Focus Inc. said it will cut its workforce by more than a third and exit certain businesses to reduce fixed manufacturing costs and quarterly losses. The company said it will close operations at its 243,000-square-foot manufacturing plant in Shenzhen, China, and will cease manufacturing and selling passive optical components. New Focus said its total workforce will drop to 390 at the end of 2002 from 900 at the end of 2001. It will take a restructuring charge of $25 million to $40 million in the first or second quarter of 2002.