Development of bismuth doped lead-aluminum-zinc-germanate glass as a broadband optical gain medium

摘要

In this paper we present the development process of a glass based on bismuth and aluminum co-doped germanate (GAB) glass. Other workers have demonstrated broadband optical gain in GAB glass. We found the addition of PbO to this glass (GAPB glass) increased the quantum efficiency (QE). Excitation of GAPB glass at 808 nm produced emission peaking at 1230 nm with a width of 260 nm, indicating the glass may be useful as a broadband optical amplifier covering the second telecoms window. The composition of each component of the GAPB glass was optimized for the QE and lifetime of this emission to produce an optimized composition of 87.4GeO_2-6Al_2O_3-6PbO-0.6Bi_2O_3 (% molar) which had a QE of 67%. However, this composition contained many white inclusions which x-ray diffraction measurements indicated were a phase separation. This would make the glass unsuitable for fibre fabrication. We tried a variety of melting condition which did not improve the glass, the melting conditions did however affect the QE and lifetime. The optimum melting conditions were 1250℃ for 30 min in a N_2 atmosphere. Next we tried adding various quantities of a variety of glass additives including SiO_2, LiO, ZnO and SrCO_3. All these additives reduced the QE, and all except SiO_2 produced a transparent glass in the appropriate quantity. The quantity of these additives which gave a transparent glass and their QE's were LiO: 10% and 6%, ZnO: 10% and 43%, SrCO_3: 5% and 27% respectively. Therefore the optimized composition for QE and transparency is 74.4GeO_2-10ZnO-6Al_2O_3-6PbO-0.6Bi_2O_3.