The origin of near-IR luminescence in bismuth-doped silica and germania glasses free of other dopants: First-principle study

First-principle study of possible bismuth-related centers in SiO2 and GeO2 glass model hosts is performed and the results are compared with the experimental data. The following centers are modeled: trivalent and divalent Bi substitutional centers; BiO interstitial molecule; interstitial ion, Bi+, and atom, Bi-0; Bi center dot center dot center dot Si - Si and Bi center dot center dot center dot Ge - Ge complexes formed by interstitial Bi atoms and glass intrinsic defects, Si - Si or Ge - Ge oxygen vacancies; interstitial dimers, Bi-2(0) and Bi-2(-). Experimental data available on bismuth-related IR luminescence in SiO2:Bi and GeO2:Bi glasses, visible (red) luminescence in SiO2:Bi glass and luminescence excitation are analyzed. A comparison of calculated spectral properties of bismuth-related centers with the experimental data shows that the IR luminescence in SiO2:Bi and GeO2:Bi is most likely caused by Bi center dot center dot center dot Si - Si and Bi center dot center dot center dot Ge - Ge complexes, and divalent Bi substitutional center is responsible for the red luminescence in SiO2:Bi. (C) 2013 Optical Society of America