Selective doping of Ni(2+) in highly transparent glass-ceramics containing nano-spinels ZnGa(2)O(4) and Zn(1+x)Ga(2−2x)Ge(x)O(4) for broadband near-infrared fiber amplifiers

Selective doping of Ni(2+) in octahedral sites provided by nanocrystals embedded in glass-ceramics (GCs) is crucial to the enhancement of broadband near-infrared (NIR) emission. In this work, a NIR emission with a full-width-at-half-maximum (FWHM) of 288 nm is first reported from ZnGa(2)O(4): Ni(2+) nano-spinels embedded GCs with excellent transparency. A comparison is made of the NIR luminescence properties of Ni(2+) doped GCs containing ZnGa(2)O(4), germanium-substituted ZnGa(2)O(4) nano-spinels (Zn(1+x)Ga(2−2x)Ge(x)O(4)), and Zn(2)GeO(4)/Li(2)Ge(4)O(9) composite nanocrystals that are free of Ga(3+). The results show that ZnGa(2)O(4): Ni(2+) GCs exhibit a significantly enhanced NIR emission. The incorporation of the nucleating agent TiO(2) is favored in terms of the increased luminescence intensity and prolonged lifetime. The possible causes for the enhancement effect are identified from the crystal structure/defects viewpoint. The newly developed GCs incorporate good reproducibility to allow for a tolerance of thermal treatment temperature and hence hold great potential of fiberization via the recently proposed “melt-in-tube” method. They can be considered as promising candidates for broadband fiber amplifiers.