Published online by Cambridge University Press: 25 February 2011
A technique is presented which addresses the problem of analyzing impurities in heavy metal fluoride glass optical fibers at the extremely low levels required for long distance applications. The procedure uses selectively excited fiber impurity luminescence (SEFIL), and is extremely sensitive due to the zero-background nature of luminescence and the long interaction lengths afforded by optical fiber. The technique has been rendered quantitative through the use of standards and the normalization of the impurity emission by the Raman scattering intensity. A SEFIL analysis of two fibers with differing origins and designs is reported. The ultimate detection limits are estimated to be <1 ppb-wt for Fe3+ and ≤ 0.001 ppb-wt for Nd3+ and Pr3+.