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

Abstract

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.