EXAFS studies of the local structure of bismuth centers in multicomponent silica glass based optical fiber preforms

• We fabricate Bi-doped alumino-silicate glass optical fiber.
• We realize yttria-alumino-silicate glass based Bi doped fiber.
• We carry out an EXAFS analysis of bismuth in silicate-glass based optical fiber preforms.
• The valence state of Bi center responsible for broadband NIR fluorescence, is established as 3 +.
• Incorporation of Y2O3 into alumino-silicate glass host does not lead to any change in Bi structure.

An Extended X-ray Absorption Fine Structure (EXAFS) analysis of the local structure of bismuth in silicate-glass based optical fiber preforms exhibiting broadband near-infrared luminescence is presented. The valence state of the bismuth ions in alumino-silicate and yttria-alumino-silicate glass hosts is revealed to be Bi3+ and the local geometry is suggested to be a trigonal oxygen pyramid with the electron lone pair positioned opposite to the oxygen atom plane. Furthermore we found that the incorporation of Y2O3 into alumino-silicate glass host does not result in any change in the surrounding Bi structure.