Raylon M. Yow

Absorption intensities and emission cross sections of Tb3+ (4f8) in TbAlO3

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 betw...

Spectroscopic analysis of the Er3+(4f11) absorption intensities in NaBi(WO4)2

A spectroscopic analysis is performed on Er3+ (4f11) ions doped in NaBi(WO4)2 (NBWO) in order to assess this material for its potential as a near-infrared laser. The Judd–Ofelt model is applied to the room-temperature absorption intensities of Er3+ (4f11) in NBWO to obtain the three phenomenological intensity parameters: Ω2=5.50×10−20 cm2, Ω4=1.00×10−20 cm2, and Ω6=0.71×10−20 cm2. The intensity parameters are then used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios for the Er3+ transitions from the excited state multiplet manifolds to the lower lying manifold states. Using the radiative decay rates for the Er3+ (4f11) transitions between the corresponding excited states and the lower lying states, the radiative lifetimes of eight excited states of Er3+ are determined in this host. Using the measured room temperature fluorescence lifetime of approximately 4.75 ms and the radiative lifetime of 5.63 ms as predicted by the Judd–Ofelt model for the 4I13/2→4I15/2 (1.52 μm) transition of Er3+ in NBWO the quantum efficiency is determined to be approximately 84% for this laser material.A spectroscopic analysis is performed on Er3+ (4f11) ions doped in NaBi(WO4)2 (NBWO) in order to assess this material for its potential as a near-infrared laser. The Judd–Ofelt model is applied to the room-temperature absorption intensities of Er3+ (4f11) in NBWO to obtain the three phenomenological intensity parameters: Ω2=5.50×10−20 cm2, Ω4=1.00×10−20 cm2, and Ω6=0.71×10−20 cm2. The intensity parameters are then used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios for the Er3+ transitions from the excited state multiplet manifolds to the lower lying manifold states. Using the radiative decay rates for the Er3+ (4f11) transitions between the corresponding excited states and the lower lying states, the radiative lifetimes of eight excited states of Er3+ are determined in this host. Using the measured room temperature fluorescence lifetime of approximately 4.75 ms and the radiative lifetime of 5.63 ms as predicted by the Judd–Ofelt model for the 4I...

Spectral analysis and energy-level structure of Er3+(4f11) in polycrystalline ceramic garnet Y3Al5O12

Absorption spectra obtained between 1550 and 440nm and fluorescence spectra obtained between 1700 and 1500nm are reported in a comparative spectroscopic study of polycrystalline ceramic Y3Al5O12 (YAG) and single-crystal laser rod YAG, both containing 50at.% Er3+ as a dopant in the garnet host. The spectra are observed in both samples at temperatures between 8K and room temperature. The detailed splitting of individual multiplet manifolds, LJ2S+1, Er3+(4f11), by the crystalline electric field is similar in both the ceramic sample and the single-crystal laser rod. With few exceptions, there is little shift in energy (few wave numbers) of individual Stark levels within a manifold, between dilute and concentrated Er3+ samples. This is not too surprising since Y3Al5O12 and Er3Al5O12 form a solid solution with the majority of Er3+ ions occupying cation sites having D2 symmetry in the garnet lattice over the entire solid solution range. As a check on the observed manifold splittings of Er3+ in ceramic YAG, we co...

Absorption intensities and emission cross section of intermanifold transition of Er3+ in Er3+:Y2O3 nanocrystals

The room temperature absorption intensities of Er3+(4f11) transitions in synthesized Er3+:Y2O3 nanocrystals have been analyzed using the Judd-Ofelt (J-O) 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 Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds LJ2S+1 of Er3+(4f11). The emission cross section of the important intermanifold Er3+ I13∕24→I15∕24 (1.5μm) transition has been determined. The room temperature fluorescence lifetime of this transition in Er3+:Y2O3 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 Er3+(4f11) ions suggests that synthesized Er3+:Y2O3 nanocrystals could be an excellent alternative to single crystal Er3+:Y2O3 for certai...

Energy-level structure and spectral analysis of Nd3+(4f3) in polycrystalline ceramic garnet Y3Al5O12

A detailed crystal-field splitting analysis is given for the 26 lowest-energy multiplet manifolds, LJ2S+1, of Nd3+(4f3) in polycrystalline ceramic garnet Y3Al5O12 (YAG). The absorption spectra obtained between 8K and room temperature, and between 1750 and 350nm, and the fluorescence spectrum obtained at 8K and observed between 1450 and 875nm are analyzed for transitions between individual energy (Stark) levels that characterize the energy-level structure of Nd3+ ions in D2 symmetry sites, replacing Y3+ ions in the garnet host lattice. A model Hamiltonian including atomic and crystal-field terms is diagonalized within the complete 4f3SLJMJ basis set which includes 364 states. The calculated splitting of the Nd3+ energy levels by the crystal field is compared with the experimental splitting observed in both the ceramic sample and a single-crystal laser rod. Both samples have approximately the same Nd3+ concentration, about 1at.%. By varying the atomic and crystal-field parameters, we obtain a standard devia...

Optical absorption intensity analysis and emission cross sections for the intermanifold and the inter-Stark transitions of Nd3+(4f3) in polycrystalline ceramic Y2O3

Spectroscopic properties have been characterized for trivalent neodymium doped polycrystalline ceramic ytttria, Nd3+:Y2O3. The Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] analysis has been applied to the room temperature absorption spectrum to determine the radiative decay rates and branching ratios of Nd3+ transitions from the F3∕24 metastable manifold to the IJ4 lower-lying multiplet manifolds. The quantum efficiency is determined from the measured fluorescence lifetime and the radiative lifetime of the F3∕24 manifold state. In addition, a detailed characterization of the Stark energy levels of the I9∕24 and I11∕24 manifolds has been performed using the room temperature fluorescence spectra for the F3∕24→I9∕24 and F3∕24→I11∕24 transitions of Nd3+(4f3) in ceramic Y2O3. The emission cross sections of the F3∕24→I9∕24 and F3∕24→I11∕24 intermanifold transitions have been determined. Also, the peak emission cross sections of the principal inter-Stark peak transitions R1→X5 and R1→Y2...

Modeling the crystal-field splitting of energy levels of Er3+(4f11) in charge-compensated sites of KPb2Cl5

A point-charge lattice-sum model corrected for induced multipoles is used to investigate the crystal-field splitting of the LJ2S+1 energy levels of Er3+(4f11) ions that occupy charge-compensated sites in the laser host crystal KPb2Cl5. Spectroscopic data are reported and analyzed for Er3+ between 1550 and 440nm at cryogenic temperatures. The crystal-field (Stark) splitting of the ground-state manifold I15∕24 and the splitting of individual excited manifolds of Er3+ are established from analyses of temperature-dependent (hot band) absorption spectra. The analyses confirm the Stark splitting of the IJ4 and F9∕24 manifolds that are reported in the literature. From an analysis of the data, it appears that only one of the two possible Pb2+ sites serving as a charge-compensated site for Er3+ is involved in the optical activity of the Er3+ ions. From an examination of the crystallographic data of KPb2Cl5, we identify a possible site for the optically active Er3+ ion in the lattice and calculate the lattice-sum c...

Comparative study of the crystal-field splitting of trivalent neodymium energy levels in polycrystalline ceramic and nanocrystalline yttrium oxide

Absorption and fluorescence spectra of commercially available polycrystalline ceramic Nd3+:Y2O3 and nanocrystalline aggregates of Nd3+:Y2O3 grown in our laboratory are optically characterized at nominal 8K and room temperature. In comparing the spectra obtained from these two different sources, we find similarities in terms of the detailed crystal-field splitting of the energy levels of the Nd3+ ion in the Y2O3 host. The 8K spectra are analyzed for the energy (Stark) level transitions between the LJ2S+1 multiplet manifolds of Nd3+(4f3). The analysis includes the manifolds of I9∕24 (the ground state), I11∕24, I13∕24, I15∕24, F3∕24, F5∕24, H9∕22, F7∕24, S3∕24, and F9∕24. The results of this study are also compared with a crystal-field splitting analysis reported earlier for single-crystal Nd3+:Y2O3 grown by a modified flame fusion method. We find that the spectroscopic properties of our composites compare favorably with other ceramic and single-crystal forms of Nd3+:Y2O3 currently available.

Analyses of the optical and magneto-optical spectra of Tb3Ga5O12

Absorption spectra of the FJ7, D4,3,25, G6,5,45, and L10,95 multiplet manifolds of Tb3+ (4f8) in D2 sites in cubic garnet Tb3Ga5O12 (TbGaG) are investigated at sample temperatures between 1.8K and room temperature. Absorption measurements extend from 5000to340nm. From analyses of temperature-dependent (hot-band) absorption spectra, many of the crystal-field split energy (Stark) levels of the LJ2S+1 multiplet manifolds of Tb3+ are identified and confirmed from analyses of the fluorescence spectra observed between 485 and 680nm, representing transitions from the D45 to the FJ7 manifolds. Each manifold is split by the crystal field into 2J+1 Stark levels. Some of these manifolds, including the ground-state manifold F67, 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 (1.8K). To resolve these spectra, we have investigated the Zeeman and magneto-optical spectra for repres...

Inter-Stark Energy Levels and Effects of Temperature on Sharp Emission Lines of Nd3+ in LiYF4

The inter-Stark components of the 4 I 9/2 and 4 I 11/2 manifolds have been characterized using the room-temperature fluorescence spectra for the 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions of Nd 3+ in LiYF 4 laser crystal. The thermal effects on the linewidths, positions, and line shifts of the inter-Stark transitions of the 908 (R 1 → X 5 ) and 1052.4 (R 1 → Y 2 ) nm lines within the respective inter-manifold transitions of 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 have been also investigated. The linewidths of these transitions are found to increase with increasing temperature. The 908 nm line is found to shift toward the shorter wavelength, while the 1052.4 nm line has shifted toward the longer wavelength. The experimental results of the temperature-dependent widths and shifts of these sharp spectral lines are explained using the phonon-ion interaction theory which assumes the Debye model for phonons in crystalline solids.