GLASS MATERIALS FOR OPTICAL FIBERS

Optical fibers represent the key component of modern optical telecommunication networks. Such fibers are based on silica glass of high purity usually modified with several percent of glassforming oxides such as GeO 2 and P 2 O 5 . These materials with minimum optical losses around 1.5 m are transparent up to ~2 m. In this paper, the attention is focused on silica glass materials doped with ions of rare-earth elemens for fiber lasers and fiber amplifiers. Since rare earths cause phase separation only in small amount incorporated into silica glass, ternary systems containing P 2 O 5 or Al 2 O 3 have been investigated. Latest results in GeO 2 -based glasses transparent in mid infrared region are also presented.