New age fiber crystals

Summary form only given. Photonic crystal fibers (PCFs - sometimes also known as "holey" or "microstructured" fibers) have been the focus of increasing scientific and technological interest since the first working example was produced in late 1995. Although superficially similar to a conventional optical fiber, PCF has a unique microstructure, consisting of an array of microscopic holes (or channels) that runs along the entire length of the fiber. These holes act as optical barriers or scatterers, which suitably arranged can "corral" light within a central core (either hollow or made of solid glass). The holes can range in diameter from ∼25 nm to ∼50 μm. Although most PCF is formed in pure silica glass, it has also recently been made using polymers and non-silica glasses, where it is difficult to find compatible core and cladding materials suitable for conventional total internal reflection guidance. PCF supports two guidance mechanisms: total internal reflection, in which case the core must have a higher average refractive index than the holey cladding; and a two-dimensional photonic bandgap, when the index of the core is not critical.