A photonic crystal fiber (PCF), which is composed of small air holes running through the fiber length, has various kinds of unique features that cannot be realized in a standard single‐mode fiber. We cannot expect more advancement in optical fiber optics without PCFs.
In this article, various important properties such as dispersion, mode‐field diameter, and the single‐mode property are reviewed. Also, applications such as dispersion‐compensating fibers, supercontinuum, and polarization‐maintaining fibers are explained.