SPRINGFIELD, Va., Nov. 28 -- Isomet Corp. has received supplemental orders worth $1.9 million to produce and supply birefringent materials to a customer in the fiber optic industry. The orders come on the heels of an October order worth $2.8 million from the same customer. Shipments for the new orders will run through December 31, 2001, the company said. Isomet is a supplier of processed birefringent crystal material and devices for laser related applications. These materials are currently being used in the fiber optics field in dense wavelength division multiplexing products.