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Tb 3+-doped fluorophosphate glasses with the composition of P 2 O 5-K 2 O-SrF 2-Al 2 O 3-x Tb 4 O 7 (where x = 0.1, 0.5, 1.0, 2.0 and 4.0 mol%) were prepared by a conventional high temperature melt quenching technique and characterized through absorption, emission, excitation and decay measurements. From the emission studies, a strong green emission at around 546 was observed, which corresponds to the 5 D 4 → 7 F 5 transition of Tb 3+ ion. Green/blue intensity ratios (I G /I B) were evaluated as a function of Tb 3+ concentration and vice versa. Higher I G /I B intensity ratio confirms the higher covalency between Tb-O bond and higher asymmetry around the Tb 3+ ions in the present fluorophosphate glasses. The decay curves for the 5 D 4 level of Tb 3+ ion were measured and found that they exhibited single exponential nature irrespective to the dopant concentration. The experimental lifetime was determined using single exponential fitting and found that it increased from 2.65 to 2.95 ms when Tb 3+ concentration increased from 0.1 mol% to 4.0 mol%. The derived properties were compared to the other Tb 3+-doped glasses in order to see the potentiality of the material for visible laser gain media at 546 nm.

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Nd 3+-doped RE 3 Ga 5 O 12 (RE = Gd, Y, and Lu) nano-crystalline garnets of 40-45 nm in size have been synthesized by a sol-gel method. With the decrease of the RE atom size, the chemical pressure related to the decreasing volumes of the GaO 4 tetrahedral, GaO 6 octahedral and REO 8 dodecahedral units drive the nano-garnets toward a more compacted structure, which is evidenced by the change of the vibrational phonon mode frequencies. The chemical pressure also increases the crystal-field strength felt by the RE 3+ ions while decreases the orthorhombic distortion of the REO 8 local environment. These effects alter the absorption and emission properties of the Nd 3+ ion measured in the near-infrared luminescence range from 0.87 to 1.43 μm associated with the 4 F 3/2 → 4 I J (J = 9/2, 11/2, 13/2) transitions. The 4 F 3/2 luminescence decay curves show non-exponential behavior due to dipole-dipole energy transfer interactions among Nd 3+ ions that increases with pressure.

Nano-crystalline lutetium gallium garnets co-doped with Dy3+ and Sm3+ ions have been synthesized via a sol–gel method and their structural, morphological and luminescence properties have been characterized.