Estimation of energy transfer parameters in thulium- and ytterbium-doped silica fibers

We present an estimation of the energy transfer coefficients by comparison of the measured emission of three TYDF samples with numerical simulations of the respective emission. The energy transfer coefficients were found higher than those reported in Tm/Yb-doped fluoride based crystals. With possible improvement of excited level lifetime of thulium by high alumina codoping, it makes Tm/Yb co-doped silica fibers promising for applications in fiber lasers and amplifiers