An optical fiber (or fibre) is a glass or plastic fibre that carries light along its length. Fibre optics is the overlap of applied science and engineering concerned with the design and application of optical fibres. Optical fibres are widely used in fibre-optic communications, which permits transmission over longer distances and at higher data rates (a.k.a "bandwidth"), than other forms of communications. Fibers are used instead of metal wires because signals travel along them with less loss, and they are immune to electromagnetic interference. Fibres are also used for illumination, and in bundles can be used to carry images, allowing viewing in tight spaces. Specially designed fibres are used for a variety of other applications, including as sensors and fibre lasers. This book presents leading research from around the world.