∼2 μm fluorescence and energy transfer characteristics in a highly Tm3+-doped bismuthate glass based on Al2O3 adjustment

In this paper, the glass network of a newly developed bismuthate glass was adjusted and analyzed by changing the Al2O3 content, thus effectively increasing the doping concentration of Tm3+. The fundamental physical and thermal properties including density, molar volume, refractive indices, and characteristic temperatures were systematically investigated, suggesting the B2O3/Al2O3 anomaly ratio of the prepared host glass is 35%/10%. Various glass network units were found in the host glasses, so that the flexibility of the glasses was enhanced, which is favorable for highly and homogeneously doping of Tm3+ ions. A highly Tm3+-doped bismuthate glass with a concentration of 20.5 × 1020 ions/cm3 was prepared without quenching. Radiative parameters of the presented glass were determined from absorbance spectra. Moreover, relatively large emission cross-section (5.29 × 10−21 cm2) and gain coefficient (10.87 cm-1) were achieved in the prepared highly Tm3+-doped bismuthate glass. Finally, the microparameters for energy transfer processes were calculated by a spectral overlap method. Results show that the presented highly Tm3+-doped bismuthate glass has ideal potential for high gain fibers in ∼2 µm band.