Square-shaped blue single crystals of nickel-doped magnesium aluminum spinel have been pulled
down from the melt, by the
micro-
pulling-
down method. The absorption spectra of doped samples show three broad absorption bands. According to the absorption map and the chemical analysis of these crystals, the effective segregation coefficients of Ni
2+ in MgAl
2O
4 at low doping concentration (C
Ni![left angle bracket](http://www.sciencedirect.com/scidirimg/entities/2329.gif)
2 mol%) were calculated to be less than the unity, due to the vaporization behavior of NiO. Strong infrared broad emission in the eye-safe region peaking at 1.3 μm have been systematically investigated under high-intensity pulsed Nd:YAG laser excitation in the red region. The suitable absorption for InGaAs laser-diode pumping combined with long decay time of the infrared emissions and the good thermal properties of MgAl
2O
4 make Ni
2+–MgAl
2O
4 a promising laser crystal.