Energy levels and intensity parameters of Ho3+ ions in Y3Al5O12 and Lu3Al5O12

Abstract The energy levels of the trivalent lanthanide Ho 3 + in Y 3 Al 5 O 12 (YAG) and Lu 3 Al 5 O 12 (LuAG) have been measured. The Stark split levels for the first nine Ho manifolds in these materials have been measured, and the results have been fit to a free ion plus crystal field Hamiltonian to generate a theoretical set of energy levels. Crystal field parameters were varied to determine the best fit between experimental and theoretical energy levels. The energy levels of Ho:LuAG are seen to be very similar to those in Ho:YAG. However, subtle changes resulting from replacing Y 3 + with Lu 3 + in the garnet crystal Y 3 Al 5 O 12 result in different transition wavelengths in LuAG. This has implications for Ho I 7 5 → I 8 5 lasers operating at ∼ 2.1 μ m . Although the energy levels have been measured previously in Ho:YAG, they have not been measured in Ho:LuAG. A comparison of the energy levels in Ho:YAG measured here show some discrepancies with previous measurements. The consistency of the energy level placements between Ho:LuAG and Ho:YAG indicate that the earlier studies may have some errors in the assignments. Finally, a Judd–Ofelt analysis is performed on Ho:YAG and Ho:LuAG to determine the intensity parameters, and thus, the transition probabilities and branching ratios of the first eight excited manifolds.

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