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An erbium-doped Lu3Ga5O12(LuGG) single crystal was grown by the Czochralski method. The crystalline phase in the grown crystal was analyzed by powder X-ray diffraction. The erbium-ion emission spectra of the crystal were acquired. The erbium-ion emission cross-section (ECS) spectrum was computed from the acquired emission spectrum. The erbium-ion absorption cross-section (ACS) spectrum was computed using the McCumber relationship. The results are discussed in contrast to those computed from the acquired absorption spectrum, and the comparison shows that both methods give consistent results. The temporal characteristics of the emissions were also studied based on 0.98 μm pulse pumping. The study shows that the infrared emissions at 1.0, 1.5, and 2.8 μm show mono-exponentially temporal behavior. Instead, the decays of two visible emissions at 0.56 and 0.67 μm show considerable non-exponential features; each trace can be fitted double-exponentially. The non-exponential behavior is associated with those erbium ions that are present in the form of clusters, which enables non-radiative upconversion depopulation and hence additional contribution to the decay through cross relaxation between the erbium ions in clusters. The study also shows that about half of the erbium ions are present in the cluster state in the studied crystal. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ doped LiNbO 3 (LN) single crystal films with varying Yb3+ doping level were grown on z -cut LiTaO 3 bulk single crystals via using e-beam evaporation method. The crystallographic orientation, elemental distribution, fluorescence properties, ionic valence states, Er3+ concentration, Yb3+ concentration and Li 2 O content of films were carefully studied. Results from XRD, SEM and Raman scattering conclude that the predominant phase of these films is LN and they are oriented along (006). The results of energy dispersive spectroscopy indicate that constituent elements are uniformly distributed over the entirety of the films. The visible and near-infrared luminescence intensities rise with increasing Yb3+-doping concentration. The Li 2 O content of films remains constant at 48.8 mol% with growing Yb3+-doping level based on the optical birefringence method, which is consistent with the Raman results. XPS results suggest that the Er3+ and Yb3+ concentrations in the films are lower than that in the polycrystalline powder since e-beam evaporation has a low efficiency of heavy Er3+ and Yb3+ ions. • The Er3+, Yb3+ doped LiNbO 3 single crystal thin films were grown by the e-beam evaporation method. • The fluorescence properties enhance clearly with a rise in Yb3+-doping concentration. • The accurate Li 2 O content have been evaluated by the birefringence method. • The Er3+ and Yb3+ concentration in the films have been calculated by the XPS. [ABSTRACT FROM AUTHOR]

We measured fluorescence spectra of visible and infrared electronic transitions at 530 (2H 11/2 → 4I 15/2), 560 (4S 3/2 → 4I 15/2), 670 (4F 9/2 → 4I 15/2), 980 (4I 11/2 → 4I 15/2), 1530 (4I 13/2 → 4I 15/2) and 2700 nm (4I 11/2 → 4I 13/2) of Er3+ in Gd 3 (Al 0.4 Ga 0.6) 5 O 12 garnet single-crystal excited at the wavelength 520 nm (for the 980 nm emission) or 980 nm (for other emissions). From measured fluorescence spectrum, Er3+ emission cross-section spectrum was calibrated for each transition. Absorption cross-section spectra were further derived on the basis of McCumber equation, and compared with those spectra obtained from measured absorption spectrum on the basis of the Beer-Lambert law. The comparison showed that the results given by two methods can be regarded as same within the error. The transient features of visible and infrared emissions were also studied under pulse excitation. The results showed that, while the three IR emissions at 980, 1530 and 2700 nm all follow a mono-exponential function, both green and red 980-nm-upconverted emissions at 560 and 670 nm exhibit non-mono-exponentially decaying feature, and each decaying trace can be fitted by a sum of two exponential functions. The non-mono-exponential feature is related to cross relaxation caused by non-radiative short-distance energy transfer between clustered Er3+ sites. • Cross-section spectra of Er3+ ions in Gd 3 (Al,Ga) 5 O 12 garnet crystal were studied. • Emission cross-section spectra are computed from measured fluorescence spectra. • Absorption cross-section spectra are derived by two ways and results are same. • 980-nm-upconverted visible emissions show non-mono-exponential transient feature. • It is caused by non-radiative energy transfer between clustered Er3+ sites. [ABSTRACT FROM AUTHOR]

A previous paper [J. Lumin. 177 (2016) 219] has studied Judd-Ofelt spectroscopic properties of Er3+ (0.5 at%)-doped Gd 3 (Al, Ga) 5 O 12 garnet single-crystal, and reported the Judd-Ofelt intensity parameters Ω 2 = 1.47 × 10−20 cm2, Ω 4 = 1.38 × 10−20 cm2 and Ω 6 = 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 Gd 3 (Al 0.4 Ga 0.6) 5 O 12 , and obtained quite different values of Judd-Ofelt intensity parameters Ω 2 = (0.34 ± 0.11) × 10−20 cm2, Ω 4 = (0.48 ± 0.16) × 10−20 cm2 and Ω 6 = (1.05 ± 0.17) × 10−20 cm2. The quite different Ω t 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 Ω t values. Quite different Ω t 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. • Er:Gd 3 (Al,Ga) 5 O 12 crystal was grown and its spectroscopic properties are studied. • Judd-Ofelt analysis was done and the result is compared with previously reported. • The Judd-Ofelt data obtained show large differences from the previously reported. • Main reason is large difference of Er3+ absorption features in two studies. • Sellmeier equation, lattice constant and segregation coefficient are presented. [ABSTRACT FROM AUTHOR]