Influence of Bi³⁺ ions on the amplification of 1.3 μm emission of Pr³⁺ ions in lead silicate glasses for the applications in second telecom window communications

The primary objective of this study is to characterize ¹G₄ → ³H₅ (1.3 μm, which is highly important in telecommunications) and also ³P₀ → ³F₂ (red emission) spectral lines of Pr³⁺ ions in lead silicate glasses sensitized with bismuth ions. The intensity of these spectral lines exhibited large amplification (nearly four times) due to co-doping with Bi³⁺ ions with fixed concentration of Pr³⁺ ions. Several radiative parameters, e.g., transition probabilities (A_ij), branching ratios (β), radiative life times (τ) and quantum efficiencies (η) of these spectral lines were evaluated using modified Judd-Ofelt theory. These parameters exhibited the maximal values when the glasses were codoped with the optimal concentration of Bi₂O₃ (5.0 mol%). The increasing population of ³P₀ and ¹G₄ levels of Pr³⁺ ions (with the gradual increase of Bi₂O₃ concentration up to 5.0 mol%) that caused the amplification of above mentioned emissions occurred: (i) due to the energy transfer from ³P₁→¹S₀ emission transition of Bi³⁺ ions and (ii) due to the increasing presence of Bi³⁺ ions in octahedral positions that are predicted to induce structural defects in the glass network. The quantitative analysis of these results together with the kinetic rate equations suggested that the Pr³⁺ ions doped lead silicate glasses mixed with (about 5.0 mol%) Bi₂O₃ are highly efficient in producing intense 1.3 μm (¹G₄ → ³H₅) narrow emission. Hence, it is concluded that the optical fibers drawn from the glasses of such compositions are highly useful for the applications in the second telecom window.