Temperature-dependent stimulated emission cross section and concentration quenching in highly doped Nd3+:YAG crystals

Measurements are reported of the spectroscopic properties (absorption and emission spectra, stimulated emission cross section, and radiative lifetime) of Nd:YAG crystals doped with 1, 2 and 3 at% Nd3+ in the temperature range between 70 and 300 K. The stimulated emission cross sections for these crystals were determined using the Fiichtbauer-Ladenburg (F-L) formula at each different temperature. The absorption spectra at room temperature were used to calculate the F-4(3/2) -> I-4(3/2) stimulated-emission cross section and the 4 F,, radiative lifetime according to Judd-Ofelt theory. As the temperature decreases the emission cross section increases, while the emission lifetime remains constant for all the samples. The temperature dependences of the stimulated emission cross sections for the differently doped crystals are in good agreement with earlier predictions. The concentration quenching effect in highly doped Nd: YAG was also addressed. Although there is concentration quenching in the highly doped Nd: YAG crystals, they are still promising efficient laser materials for high-power microchip solid-state lasers. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.