Re-study of Judd-Ofelt spectroscopic properties of Er3+-doped Gd3(Al, Ga)5O12 single crystal

Abstract A previous paper [J. Lumin. 177 (2016) 219] has studied Judd-Ofelt spectroscopic properties of Er3+ (0.5 at%)-doped Gd3(Al, Ga)5O12 garnet single-crystal, and reported the Judd-Ofelt intensity parameters Ω2 = 1.47 × 10−20 cm2, Ω4 = 1.38 × 10−20 cm2 and Ω6 = 1.19 × 10−20 cm2. We have performed a re-study on the Judd-Ofelt spectroscopic properties of a similar garnet single-crystal Er3+(20 at%)-doped Gd3(Al0.4Ga0.6)5O12, and obtained quite different values of Judd-Ofelt intensity parameters Ω2 = (0.34 ± 0.11) × 10−20 cm2, Ω4 = (0.48 ± 0.16) × 10−20 cm2 and Ω6 = (1.05 ± 0.17) × 10−20 cm2. The quite different Ωt values given by two studies are mainly due to remarkably different absorption characteristics of Er3+ in the crystals employed in two studies, and factors that lead to quite different absorption characteristics are discussed. Another reason is that the hypersensitive transition at 380 nm was excluded from the Judd-Ofelt calculation in that paper, resulting in deviation of their result. Instead, all of the Er3+ absorption bands were included in our calculation, allowing to obtain more accurate Ωt values. Quite different Ωt values lead to considerable differences of relevant spectroscopic parameters, such as radiative rates and lifetimes of typical Er3+ emissions, for which the difference from each other is as much as three times. In addition, visible, near-infrared and mid-infrared fluorescence spectra and lifetimes of Er3+ in the studied crystal were measured, and the emission characteristics are discussed.