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L 10,9 multiplet manifolds of Tb 3+ ͑4f 8 ͒ in D 2 sites in cubic garnet Tb 3 Ga 5 O 12 ͑TbGaG͒ are investigated at sample temperatures between 1.8 K and room temperature. Absorption measurements extend from 5000 to 340 nm. From analyses of temperature-dependent ͑hot-band͒ absorption spectra, many of the crystal-field split energy ͑Stark͒ levels of the 2S+1 L J multiplet manifolds of Tb 3+ are identified and confirmed from analyses of the fluorescence spectra observed between 485 and 680 nm, representing transitions from the 5 D 4 to the 7 F J manifolds. Each manifold is split by the crystal field into 2J + 1 Stark levels. Some of these manifolds, including the ground-state manifold 7 F 6 , consist of Stark levels that are accidentally degenerate, or nearly so, making transitions to or from these levels appear as unresolved spectra, even at the lowest temperature investigated ͑1.8 K͒. To resolve these spectra, we have investigated the Zeeman and magneto-optical spectra for representative manifolds 5 D 4 , 7 F 5 , and 7 F 6 at temperatures of 78 and 85 K and magnetic fields up to 7 kOe. The data are interpreted using the Stark levels and wave functions from a crystal-field splitting calculation that involved 80 individual Stark levels identified from the optical spectra of the 7 F J and quintet states reported in this study. Good agreement is obtained between the calculated and the experimental Stark levels. The calculated energy and symmetry label for each Stark level in the 5 D 4 , 7 F 5 , and 7 F 6 manifolds suitably interpret the spectral properties observed in the magneto-optical spectra, including the experimental assignment reported in the literature for the ground state as a quasidoublet ͕⌫ 1 , ⌫ 2 ͖.

Trivalent terbium absorption intensities in single-crystal TbAlO3 are analyzed using the Judd-Ofelt model to assess the crystal’s potential as a solid state laser system. The standard Judd-Ofelt model was applied to the room temperature absorption intensities of Tb3+ (4f8) to determine the phenomenological intensity parameters Ω2, Ω4, and Ω6. Seven multiplet manifolds are identified and the absorption intensities of these manifolds are least-squares fitted to the calculated intensities to obtain the intensity parameters: Ω2=40.52×10−20cm2, Ω4=8.74×10−20cm2, and Ω6=2.26×10−20cm2 in TbAlO3. These intensity parameters are then applied to determine the radiative decay rates and branching ratios of Tb3+ transitions from the D45 to the FJ′7 multiplet manifolds. Based on the results, the radiative lifetime of the excited state manifold D45 is determined from the radiative decay rates and found to be 3.5ms. The calculated lifetime is longer than the measured lifetime, reflecting the nonradiative interactions between the Tb3+ ions and the lattice in the pure compound. The intensity parameters, radiative lifetime, and emission cross sections are then compared to those reported in other laser hosts. The quantum efficiency of the laser transition D45→F57 of Tb3+ is approximately 57.0% in TbAlO3.

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Optical absorption intensity analysis and emission cross sections for the intermanifold and the inter-Stark transitions of Nd 3 + ( 4 f 3 ) in polycrystalline ceramic Y 2 O 3 Optical-absorption intensities and intermanifold emission cross sections of trivalent erbium ions in calcium fluorophosphate J. Appl. Phys. 98, 033535 (2005); 10.1063/1.2005382 Absorption intensities and emission cross sections of principal intermanifold and inter-Stark transitions of Er 3 + ( 4 f 11 ) in polycrystalline ceramic garnet Y 3 Al 5 O 12The room temperature absorption intensities of Er 3+ ͑4f 11 ͒ transitions in synthesized Er 3+: Y 2 O 3 nanocrystals have been analyzed using the Judd-Ofelt ͑J-O͒ model in order to obtain the phenomenological intensity parameters. The J-O intensity parameters are subsequently used to determine the radiative decay rates, radiative lifetimes, and branching ratios of the Er 3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds 2S+1 L J of Er 3+ ͑4f 11 ͒. The emission cross section of the important intermanifold Er 3+ 4 I 13/2 → 4 I 15/2 ͑1.5 m͒ transition has been determined. The room temperature fluorescence lifetime of this transition in Er 3+ :Y 2 O 3 nanocrystals was measured. From the radiative lifetime determined from the J-O model and measured fluorescence lifetime, the quantum efficiency of this material was determined. The comparative study of Er 3+ ͑4f 11 ͒ ions suggests that synthesized Er 3+: Y 2 O 3 nanocrystals could be an excellent alternative to single crystal Er 3+: Y 2 O 3 for certain applications especially in the near infrared region.