Optical transitions and absorption intensities of Dy 3+ (4f 9) in YSGG laser host

Abstract

Spectroscopic and laser properties of Dy 3+-doped in Y 3Sc 2Ga 3O 12 (YSGG) are characterized by employing the Judd–Ofelt theory. The Judd–Ofelt model has been applied to the room temperature absorption intensities of Dy 3+ (4f 9) transitions to obtain the three phenomenological parameters (referred to as Judd–Ofelt intensity parameters), from which the spectroscopic quality factor for Dy 3+ in YSGG is determined to be 0.68. The intensity parameters are used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios of the Dy 3+ transitions from the excited state manifolds to the corresponding lower-lying multiplet manifolds. Using the radiative decay rates for the Dy 3+ transitions between the excited states and the lower-lying manifold states in YSGG, radiative lifetimes of the excited states are determined. The room temperature fluorescence lifetimes of the 4F 9/2→ 6H 13/2 and 4F 9/2→ 6H 15/2 transitions of Dy 3+ in YSGG are measured to approximately 1.5 ms. We have calculated the radiative lifetime of 2.36 ms for the 4F 9/2 manifold state using the Judd–Ofelt model. Therefore, the quantum efficiency of Dy 3+ in YSGG is determined to be approximately 59%.