Preparation, structure, and spectroscopic properties of Nd3+:{La1-xLux}3

Abstract

Single crystals of lanthanum lutetium gallium garnet (LaLuGaG) were grown by the Czochralski pulling technique. X-ray diffraction and elemental analysis performed on these samples indicate that these garnets do not form with simple stoichiometry described as {La${\mathrm{}}}_{3}$[Lu${]}_{2}$${\mathrm{Ga}}_{3}$${\mathrm{O}}_{1}$2 but with increased Lu concentration in the dodecahedral site and Ga occupancy in the octahedral site. Optical absorption and fluorescence spectra confirm these results, showing inhomogeneous broadening of the spectral lines of ${\mathrm{Nd}}^{3+}$. Various laser gain measurements were performed on {${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Lu}}_{\mathit{x}}$${\mathrm{}}}_{3}$[${\mathrm{Lu}}_{1}$-y${\mathrm{Ga}}_{\mathit{y}}$${]}_{2}$${\mathrm{Ga}}_{3}$${\mathrm{O}}_{12}$ crystals containing 4.3 and 1.3 at. % ${\mathrm{Nd}}^{3+}$ to determine the usefulness of this material as a laser. No optical gain was observed. Time-resolved, site-selection spectroscopy measurements were performed to determine the effects of ion-ion interaction, and show the presence of very weak energy transfer between ions in nonequivalent crystal-field sites. Two-photon excitation spectroscopy measurements demonstrate the presence of very strong two-photon--absorption transitions, which prevents lasing in this garnet.