TIME-RESOLVED 3.10 EV LUMINESCENCE IN GERMANIUM-DOPED SILICA GLASS

In this letter we present time resolved measurements of the 3.10 eV (400 nm) photoluminescence in germainum-doped silica. The 3.10 eV band arises from a triplet to singlet transition in a GeO defect. We find that the photoluminescence decays with a time constant of around 100 mus. There is a delay roughly 10 mus in duration between excitation and the appearance of maximum photoluminescence intensity. This is evidence that an additional energy state contributes to the radiative decay of the triplet state. This state can exist within the same defect or it can exist in another defect and transfer energy to the GeO.