Centres of broadband near-IR luminescence in bismuth-doped glasses

Interstitial negative-charged bismuth dimers, Bi2- and Bi22-, are suggested as a model of broadband near-IR luminescence centres in bismuth-doped glasses. The model is based on quantum-chemical calculations of equilibrium configurations, absorption, luminescence and luminescence excitation spectra of the dimers in an alumosilicate network and is supported by IR and visible luminescence observed for the first time in bismuth-doped polycrystalline magnesium cordierite and by Raman spectra measurements in optical fibres with bismuth-doped alumosilicate glass core.