The high-resolution spectroscopic and emission-decay investigation of highly concentrated (up to 9 at. %) Nd:YAG ceramics indicates that the state of the Nd<sup>3+</sup> ion in these materials is similar to that of diluted crystals. The increased relative intensities of the spectral satellites connected with ensembles of Nd ions in near-lattice sites at high Nd concentrations C<sub>Nd</sub> is consistent with the predictions of the statistics of the random placement of these ions at the available lattice sites. The room-temperature transmission spectra show that the resonant pump in the emitting level <sup>4</sup>F<sub>3/2</sub>, including the hot-band pump <i>Z</i><sub>2</sub> → <i>R</i><sub>1</sub> and <i>Z</i><sub>3</sub> → <i>R</i><sub>2</sub>, can be efficient at high <i>C</i><sub>Nd</sub>, with important effects in the reduction of the pump quantum defect and of the corresponding heat generation under the pump. The accelerated <sup>4</sup><i>F</i><sub>3/2</sub> emission decay at high <i>C</i><sub>Nd</sub> is consistent with the increased efficiency of the energy transfer, including the contribution of migration-assisted transfer processes. The calculated emission quantum efficiency η and the figure of merit η<i>C</i><sub>Nd</sub> indicate that the concentrated Nd:YAG components can be used for construction of efficient solid-state lasers in free-generation or low-storage regimes, and, coupled with the hot-band resonant pump in the emitting level, they could enable the scaling of Nd:YAG lasers to high powers.
© 2002 Optical Society of America
(140.3380) Lasers and laser optics : Laser materials
(140.3530) Lasers and laser optics : Lasers, neodymium
(160.5690) Materials : Rare-earth-doped materials
(300.6280) Spectroscopy : Spectroscopy, fluorescence and luminescence
Voicu Lupei, Aurelia Lupei, Serban Georgescu, Bogdan Diaconescu, Takunori Taira, Yoichi Sato, Sunao Kurimura, and Akio Ikesue, "High-resolution spectroscopy and emission decay in concentrated Nd:YAG ceramics," J. Opt. Soc. Am. B 19, 360-368 (2002)