∼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 Al 2 O 3 content, thus effectively increasing the doping concentration of Tm 3+ . The fundamental physical and thermal properties including density, molar volume, refractive indices, and characteristic temperatures were systematically investigated, suggesting the B 2 O 3 /Al 2 O 3 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 Tm 3+ ions. A highly Tm 3+ -doped bismuthate glass with a concentration of 20.5 × 10 20 ions/cm 3 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 cm 2 ) and gain coefficient (10.87 cm -1 ) were achieved in the prepared highly Tm 3+ -doped bismuthate glass. Finally, the microparameters for energy transfer processes were calculated by a spectral overlap method. Results show that the presented highly Tm 3+ -doped bismuthate glass has ideal potential for high gain fibers in ∼2 µm band.