Photonic crystal fibers.
Photonic crystal fibers guide light by corralling it within a periodic array of microscopic air holes that run along the entire fiber length. Largely through their ability to overcome the limitations of conventional fiber optics-for example, by permitting low-loss guidance of light in a hollow core-these fibers are proving to have a multitude of important technological and scientific applications spanning many disciplines. The result has been a renaissance of interest in optical fibers and their uses.