Selective doping of Ni2+ in highly transparent glass-ceramics containing nano-spinels ZnGa2O4 and Zn1+x Ga2−2x Ge x O4 for broadband near-infrared fiber amplifiers

Abstract

Selective doping of Ni2+ 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 ZnGa2O4: Ni2+ nano-spinels embedded GCs with excellent transparency. A comparison is made of the NIR luminescence properties of Ni2+ doped GCs containing ZnGa2O4, germanium-substituted ZnGa2O4 nano-spinels (Zn1+xGa2−2xGexO4), and Zn2GeO4/Li2Ge4O9 composite nanocrystals that are free of Ga3+. The results show that ZnGa2O4: Ni2+ GCs exhibit a significantly enhanced NIR emission. The incorporation of the nucleating agent TiO2 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.

Correlation between ultrabroadband near‐infrared emission and Yb3+/Ni2+ dopants distribution in highly transparent germanate glass‐ceramics containing zinc gallogermanate nanospinels

“…This is reflected by the variations in the absorption bands related to Ni 2+ . The bands centered at 428, 830, and 1686 nm in the PG are ascribed to the presence of the trigonal bipyramid fivefold and tetrahedral fourfold coordinated Ni 2+ . After crystallization, completely new absorption bands centered at 610, and 1050 nm are formed in the GC, which can be attributed to the spin‐allowed 3 A 2 (F)→ 3 T 1 (F) and 3 A 2 (F)→ 3 T 2 (F) transitions of Ni 2+ in octahedral sites, in agreement with previous reports .…”

“…However, it is difficult to determine unambiguously the exact Zn 1+ x Ga 2−2 x Ge x O 4 phase formed, owing to the undistinguishable XRD patterns between the two end‐members, viz., ZnGa 2 O 4 ( x = 0) and Zn 2 GeO 4 ( x = 1) . By comparing the Raman spectra of the GC with those of the standard ZGGO polycrystals synthesized by solid‐state reaction, we have previously confirmed the formation of the Zn 1+ x Ga 2−2 x Ge x O 4 NCs with x ≥ 0.4 in the studied GC . The precipitated NCs are of cubic shape and distributed uniformly in the GC as shown in the bright‐field TEM image (Figure C).…”

Crystallization control in Ni2+‐doped glass‐ceramics for broadband near‐infrared luminesce

“…On the basis of the crystal field theory, Ni 2+ dopant potentially shows broadband emission in the NIR region. The broadband emission of Ni 2+ ions in oxide and oxyfluoride glass systems has been widely studied, and the broadband NIR luminescence has been experimentally demonstrated . Oxyfluoride glass‐ceramics are attractive because the low phonon energy of oxyfluoride crystals in glass usually leads to the low nonradiative relaxation rate of active ions.…”

Transmission electron microscopic and optical spectroscopic studies of Ni2+/Yb3+/Er3+/Tm3+ doped dual‐phase glass‐ceramics

“…This is reflected from the variations in the absorption bands related to Ni 2+ . The bands centered at 436, 860, and 1710 nm in the PG are ascribed to the presence of the trigonal bipyramid fivefold and tetrahedral fourfold coordinated Ni 2+ as in silicate glasses . After crystallization, completely new absorption bands centered at 356, 610, and 1050 nm are formed in the GC, which can be attributed to the spin‐allowed 3 A 2 (F) → 3 T 1 (P), 3 A 2 (F) → 3 T 1 (F) and 3 A 2 (F) → 3 T 2 (F) transitions of Ni 2+ in octahedral sites, in agreement with previous reports on Ni 2+ ‐doped Ga 2 O 3 NCs .…”