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Terbium (Tb 3+ ) ions are promising for the development of visible lasers. We report on the spectroscopy of Tb 3+ in the monoclinic KYb(WO 4 ) 2 (KYbW) crystal, including the Judd-Ofelt (J-O) modelling of the transition probabilities, evaluation of the absorption and stimulated-emission (SE) cross-sections with polarized light, and emission lifetime study. Within the strong configuration interaction (SCI) approximation of the J-O theory, the intensity parameters of Tb 3+ are Ω 2 =0.864, Ω 4 =1.657, Ω 6 =1.975 [10 -20 cm 2 ] and Δ=38810 cm –1 . The maximum σ abs for the 7 F 6 → 5 D 4 transition reaches 2.3×10 -21 cm 2 at 486.7 nm and the maximum σ SE for the green emission according to the 5 D 4 → 7 F 5 transition is 2.3×10 -21 cm 2 at 549.3 nm (both for E || N m ). The measured lifetime of the 5 D 4 state for a 1 at% Tb 3+ doping is 395±5 μs. Under blue excitation, Tb: KYbW exhibits intense green emission with the CIE 1931 coordinates of (0.312; 0.644). [ABSTRACT FROM AUTHOR]

We report on the crystal growth, structure determination and the vibronic and spectroscopic properties of a novel red-emitting anisotropic crystal featured by a layered structure, the Eu 3+ -doped orthorhombic potassium yttrium double molybdate crystal, KY(MoO 4 ) 2 . The transition probabilities of Eu 3+ ions are determined within the Judd-Ofelt theory. The stimulated-emission cross-sections are calculated for the 5 D 0 → 7 F J transitions of Eu 3+ with polarized light. The maximum σ SE reaches 11.4 × 10 −20  cm 2  at 613.9 nm for E || c . The strong anisotropy of the spectroscopic properties of Eu 3+ is attributed to the layered structure of KY(MoO 4 ) 2 . The lifetime of the 5 D 0 state is 0.65 ms. Under UV excitation, Eu:KY(MoO 4 ) 2 provides red emission ( CIE 1931 coordinates, x  = 0.665 and y  = 0.335) with almost unity color purity. Eu 3+ ions are studied as structural probes, revealing a single type of site (C 2 symmetry). The polarization-anisotropy of the purely magnetic-dipole 5 D 0 → 7 F 1 transition is discussed. Eu:KY(MoO 4 ) 2 is promising for red phosphors and deep-red lasers. [ABSTRACT FROM AUTHOR]

The spectroscopic properties of Tb 3+ ions in monoclinic KLu(WO 4 ) 2 double tungstate crystal are studied with polarized light. The absorption spectra in the visible, near- and mid-IR including the transitions to all lower-lying 7 F J ( J  = 0 … 5) excited states are measured. The maximum absorption cross-section for the 7 F 6  →  5 D 4 transition is 3.42 × 10 −21  cm 2  at 486.7 nm for light polarization E || N m . The transition probabilities for Tb 3+ ions are calculated within the Judd-Ofelt theory modified for the case of an intermediate configuration interaction (ICI). The radiative lifetime of the 5 D 4 state is 450 μs and the luminescence quantum yield is >90%. The polarized stimulated-emission cross-section spectra for all 5 D 4  →  7 F J ( J  = 0 … 6) emission channels are evaluated. The maximum σ SE is 11.4 × 10 −21  cm 2  at 549.4 nm (for E || N m ). Tb 3+ :KLu(WO 4 ) 2 features high transition cross-sections for polarized light being promising for color-tunable visible lasers and imaging. [ABSTRACT FROM AUTHOR]