ABSTRACT
One of the major technological advances in laser systems was the development of fibre optics [1]. This allowed laser light to be accurately and efficiently delivered to distant targets over ranges from several millimetres to many kilometres. The combination of laser sources and fibre optic delivery systems has led to important applications such as modern telecommunication systems and non-invasive laser surgery. The next step in this technology development is to combine the fibre delivery system and the laser into one device. Since fibres are made out of glass, they can act as the host material for rare earth laser ions to make fibre lasers. All of the fundamental science and technology of rare-earth-doped glass laser materials discussed in Chapter 1 are relevant for fibre lasers. The major difference is that the length of a single pass of light in a fibre laser is much longer than in a rod or slab laser. This requires significantly different resonator design techniques.
