Kompetenzzentrum für optische Spezialfasern

Energy-transfer parameters in a thulium-ytterbium doped single mode silica fiber have been determined quantitatively for the first time, to our knowledge. The principal energy-transfer parameters, estimated from spectroscopic measurements and on the basis of a migration-assisted energy-transfer model, lead to design and optimization of the thulium-ytterbium doped fiber lasers and amplifiers. Linear dependence of the energytransfer probability on the product of co-dopant concentrations proves the accuracy of the implementation of the migration-assisted energy-transfer model. It has been found that the step-wise energy-transfer process as well as emission at wavelength ranges of 475, 800, and 2000 nm with pumping at 980 nm is strongly guided by the level of ytterbium concentration with respect to thulium. Thus the proportion has been optimized on the basis of emission at the mentioned wavelength ranges, and an amplified spontaneous emission experiment performed at 2000 nm shows good agreement with the optimization result.