A thorough investigation of the emission and absorption spectra of the ( 3 F 4 , 3 H 6 ) band in thulium doped silica fibers has been performed. All the basic parameters of thulium in silica have been extracted with the purpose of further analysis in laser and amplifier simulations. The experimental methods used to obtain the scaled cross sections have been carefully selected in order to avoid problems associated with calibrated measurements and knowledge of the radiative lifetime. The values

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... the absorption cross sections agree well with previously reported values, however the peak emission to peak absorption cross section ratios are found to be significantly below 1. Also confinement factors and thulium concentrations are estimated from the results.