An optical fibre is a flexible, transparent fibre made of silica or plastic. Optical fibres are often used as a means to transmit light between the two ends of the fibre and find wide use in fibre-optic communications. They allow transmission over greater distances and at higher bandwidths than electrical cables. Fibres are used instead of metal wires because the signals travel through them with less loss, and they are immune to electromagnetic interference. Specially designed fibres are also used for many other applications, some of them being fibre optic sensors and fibre lasers. The ever growing need of advanced technology is the reason that has fueled the research in the field of optical fibre in recent times. This book strives to provide a fair idea about this discipline and to help develop a better understanding of the latest advances within this field. As optical fibre technology is evolving at a rapid pace, its contents will help the readers understand the modern concepts and applications of the subject.