New fibers will bring out the best in long-haul and metropolitan network components. As the technology of transmitting and receiving light continues to evolve and improve, so will the technology of designing new and improved optical fibers. A variety of optical fiber designs -- ranging from improved standard single-mode fibers to advanced longhaul, high-data-rate fibers -- have been introduced in the last decade. To keep pace with the rapidly increasing bandwidth demand, fiber manufacturers must introduce new, more advanced designs that will lend themselves to different types of technologies and even different metrics for measuring cost.