The effect of Nd concentration on the spectroscopic and emission decay properties of highly doped Nd : YAG ceramics - art. no. 092102

High-resolution optical spectroscopy shows that no additional defects or la rge-scale deformations take place in Nd:YAG ceramics doped with up to 9 at. % Nd as compared to the diluted single crystals. Spectral satellites conne cted with ensembles of Nd ions, predicted by the statistics of a random dis tribution over the available lattice sites, are observed at low temperature s. At higher temperatures the resolution is lost and these ensembles contri bute to an inhomogeneous broadening of the lines. At room temperature the g lobal emission decay of F-4(3/2) is nonexponential and can be explained by the common effect of a direct donor-acceptor transfer process with paramete rs deter-mined earlier for diluted crystals and by a migration-assisted tra nsfer whose ensemble-averaged rate depends quadratically on the Nd concentr ation C-Nd. The calculated quantum efficiency eta and the figure of merit e taC(Nd) indicate that concentrated Nd:YAG components are suitable for conti nuous-wave laser emission and, coupled with resonant hot band pumping into the emitting level, they show the prospect for scaling Nd:YAG lasers to ver y high powers.