Compositional dependence of the 1.3 mu m emission and energy transfer mechanism in Ge-Ga-S glasses doped with Pr3+

Effects of concentration on the amplification efficiency at 1.3 mu m were i nvestigated in Ge-Ga-S glass doped with 100-5000 ppm (in wt.) Pr3+. Quantum efficiencies and figure-of-merits (sigma(g)tau(m)) increased from 49%, 26. 3 +/- 0.5 x 10(-25) cm(2) s to 66%, 31.1 +/- 0.5 x 10(-25) cm(2) s, respect ively, with sulfur concentration decreasing from 69 to 63 at.%. Optimum com positions of the host glasses are Ge32Ga5S63 and Ge28Ga20S62 (at.%). Concen tration of Pr3+ must be <500 ppm in weight to minimize detrimental cross re laxation, which is the major energy transfer process in glasses. A linear d ependence of the reduced diffusion coefficients indicated an inhomogeneous distribution of Pr3+ in glasses. (C) 1999 Elsevier Science B.V. All rights reserved.