Study on structural, optical and gain properties of 1.2 and 2.0 μm emission transitions in Ho3 + doped tellurite glasses

• Thermally stable Ho3 + doped TeO2–Bi2O3–ZnO–Li2O–Nb2O5 (TBZLN) glasses were prepared.
• Optical absorption, NIR and visible luminescence and decay profiles were analyzed.
• 1.0 mol% Ho3 + doped TBZLN glass exhibited better lasing properties.

Holmium (Ho3 +) ions doped tellurite (TBZLN) glasses in the chemical composition (78 − x)TeO2 + 4.5Bi2O3 + 5.5ZnO + 10.5Li2O + 1.5Nb2O5 + xHo2O3 where x = 0.05, 0.1, 0.5, 1.0, 1.5 mol% were prepared by melt quenching technique and a detailed study on spectroscopic properties were reported. The characterization of prepared glasses was realized by optical absorption, fluorescence, decay profiles, X-ray diffraction (XRD), differential thermal analysis (DTA), Raman and Fourier transform infrared (FTIR) spectroscopic techniques. Absorption spectra have been analyzed by using Judd–Ofelt (J–O) theory and estimated intensity parameters, Ω2, Ω4 and Ω6, are compared with other reported glasses. The radiative properties such as radiative transition probabilities (Arad), branching ratios (β) and radiative lifetimes (τR) for certain excited states of Ho3 + ion are calculated by using intensity parameters. The NIR and visible emission spectra were used to estimate the stimulated emission cross-sections for 5I7 → 5I8,5F4(5S2) → 5I5, 5I6 → 5I8, 5F4(5S2) → 5I6, 5F5 → 5I8 and 5F4(5S2) → 5I8 transitions. Decay curve analysis was reported for 5I6, 5F4(5S2) and 5F5 levels of Ho3 + ions. Gain coefficient was calculated for 5I6 → 5I8 and 5I7 → 5I8 transitions which arise at 1.2 μm and 2.0 μm, respectively. The analysis of present studied glasses suggests that 1.0 mol% Ho3 + doped TBZLN glass exhibits relatively better lasing properties than other reported glasses and is favorable for photonic applications.