Photonic crystal fibers and their applications in optical communications and sensors

Optical communications and sensing systems have required optical fibers to meet the demanding applications day by day, such as high bit rates, dense wavelength division multiplexing (DWDM) and long distance, so that there could be always renewed interest in fiber designs to lift fundamental limitations of silica optical fibers. One kind of fiber, which is different from the conventional fiber, is silica photonic crystal fiber (PCF) that has an array of microscopic air-holes running along its length. For PCF, there are two distinct classes as the guidance; one is using a type of total internal refection which is referred to the terms microstructured fiber, holey fiber, effective-index fiber, and hole-assisted fiber, and the other is employing photonic band-gap which is referred to photonic band-gap, Bragg fiber, and omni-directional waveguide. In this paper, we will address recent advances in PCFs. While the potential applications are also addressed, the emphasis will be on PCFs for applications in optical communications and sensing systems.