OXFORDSHIRE, England, July 3 -- Bookham Technology, which acquired Marconi’s optical component business earlier this year, said it will close its plants in Maryland (US) and Swinton to focus on manufacturing ASOC components at its Milton facility and active components at its Caswell site. The company said it can now handle component production rates of $306 million at Milton and similar levels at Caswell, due to ongoing cost-reduction efforts as part of its restructuring.