Synthesis and Spectroscopic Investigation of Yb/sup 3+/-Er/sup 3+/-Codoped LaLiP/sub 4/O/sub 12/ Glasses Relevant for Laser Applications

We are involved in Yb'*-E?sodoped phosphate glass research for eye-de laser source near 1535 nm, wavelength corresponding to the 'Ilt7+'l13~ E? transition [I]. Undoped and doped glasses of the composition Laz03-Li20-P20,, with L ~ L ~ P , O I ~ fonnulq have been synthesised. Absorption tiom the 'Ii5? E+and 'F,,? Yb" ground states have been investigated. Under pumping Yb'' ions at 975 q we have studied both E? ion emission spectra and excited state dynamics ~ f ' l ~ ~ , ~ and *Ilm E? ion levels. The emission cross-mtion of the 'Im+'Its> transition at 1535 mn is high. A comparison with the 'Ill?+'Lz excited state absorption @SA) band shows that there is no overlap between them. This mthat this ESA will not perturb the emission around 1535 mn. The ludd-Ofell intensiry parameters R, (1 = 2, 4, 6) for E? ions have been calculated in order to duermine the radiative lifetimes, the branching ratios of the transitions and the oscillator strength ofthe excited state absorption %2-+'h Similar results for n, have been found previously P I The hieh Iiequency Raman peak shape, localised around 1200 cm", is well defined and then, this enables U% to conclude that such glass is more ordered than ofher glasses. In addition, the thermal conductivity is high for a phosphate glass. In order to characterise the laser performances of this new glarq we are planning to measure gain parmeters.