Abstract

Since 2001[1] Bi doped silicate glasses are known to exhibit ultrawideband (1–1.6 microns) emission and long (~1 ms) luminescent lifetime. The interest to these materials has greatly increased after efficient tunable laser action has been obtained in MCVD-fabricated Bi-doped silica fibers [2]. Despite numerous investigations, the nature of bismuth near infrared luminescent centers (BLC) is still a question. Different authors attribute the NIR luminescence to Bi⁺ , Bi²⁺ , Bi⁵⁺ ions or BiO complexes. One of the hypotheses [3] attributes the IR luminescence to Bi₂⁻ or Bi₂²⁻ ion dimers in the glass host. The goal of this paper is to make a contribution to the problem by examination of the synthesis conditions influence on the optical properties of the glass. For our experiments we have chosen 12% mol. MgO + 30% mol. Al₂O₃ + 57% mol SiO₂ glass composition with additional Bi₂O₃ doping. This compiosition corresponds to ternary euthectic point with melting temperature 1350°C. The samples (~50g each) were sintered for 4 hours starting from reagent-grade oxide powders in alumina crucibles in air. After the synthesis the crucibles were extracted from the oven and cooled in air. The resulting scatter- and inclusions-free pink-colored glass was annealed starting from 700°C. 2-mm thick polished plates were fabricated of all the synthesized glasses. Two sample series were prepared:

© 2009 IEEE