Luminescence properties and application of near-infrared Er3+-doped bismuth germanate laser glass

Abstract

Er³⁺-doped bismuth germanate laser materials were prepared using the conventional high-temperature melt-quenching method. The results of both the DSC and XRD analyses demonstrate that bismuth germanate glasses exhibit optimal thermal stability and a good amorphous phase. In a subsequent analysis, the internal topology of the laser glass was deduced through the integration of Raman spectroscopy. This analysis revealed that the incorporation of H₃BO₃ and Al₂O₃ could enhance the thermodynamic properties of the glass. The J-O theory calculations yielded the following parameters: intensity parameter Ω₂ = 6.49 × 10⁻²⁰cm², quality factor χ = 1.00, spontaneous radiation probability A_rad = 449.40 s⁻¹, and fluorescence lifetime τ_rad = 2.23 ms. The data demonstrate superiority over other glass systems. In order to study the luminescence characteristics of Er³⁺ in the near-infrared band, the absorption and emission cross sections as well as the gain coefficient curves were calculated based on the absorption and emission spectra. Meanwhile, the microscopic energy transfer coefficient C_D-A (1.34 × 10⁻³⁸ cm⁶/s) for the CR process between Er³⁺ was calculated according to Dexter's theory. In addition, the laser glass prepared in this paper was applied in a multi-core photonic crystal fiber, and the inter-core crosstalk XT (−56.8 dB), the effective mode-field area A_eff (363 μm²), and the photovoltaic field strengths were quantitatively computed and analyzed by the beam propagation method (BPM) and the finite element method (FEM). The results show that bismuth germanate glass is an excellent gain medium for realizing high-quality laser emission of Er³⁺ in the near-infrared band.