Properties, preparation and applications of low-loss optical fibres containing rare-earth ions

Traditionally little attention was paid to glasses doped with rare-earth ions because of their scarcity and lack of visible colouration. Some interest was stimulated by the demonstration of laser action in a neodymium-doped glass in 1961. Recently, however, the development of novel fabrication techniques for introducing high concentrations of rare-earth ions into low-loss optical fibres has aroused tremendous interest. Several methods of preparation have been proposed but the solution-doping technique developed at Southampton, is now employed world-wide. Subsequent application of these fibres has led to many new devices, both passive and active (e.g. temperature senors and lasers)