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Improvement of 4I11/2 → 4I13/2 Transition Rate and Thermal Stabilities in Er3+‐Doped TeO2‐B2O3 (GeO2)‐ZnO‐K2O Glasses

Spectroscopic and thermal analysis indicates that tellurite glasses doped with B2O3 and GeO2 are promising candidate host materials for wide‐band erbium doped fiber amplifier (EDFA) with a high 980 nm pump efficiency. In this study, we measured the thermal stabilities and the emission cross‐sections for Er3+: 4I13/2 → 4I15/2 transition in this tellurite glass system. We also determined the Judd‐Ofelt parameters and calculated the radiative transition rates and the multiphonon relaxation rates in this glass system. The 15 mol% substitution of B2O3 for TeO2 in the Er3+‐doped 75TeO2‐20ZnO‐5K2O glass raised the multiphonon relaxation rate for 4I11/2 → 4I13/2 transition from 4960 s−1 to 24700 s−1, but shortened the lifetime of the 4I13/2 level by 14 % and reduced the emission cross‐section for the 4I13/2 → 4I15/2 transition by 11%. The 15 mol% GeO2 substitution in the same glass system also reduced the emission cross‐section but increased the lifetime by 7%. However, the multiphonon relaxation rate for 4I11/2 → 4I13/2 transition was raised merely by 1000 s−1. Therefore, a mixed substitution of B2O3 and GeO2 for TeO2 was concluded to be suitable for the 980 nm pump efficiency and the fluorescence efficiency of 4I13/2 → 4I15/2 transition in Er3+‐doped tellurite glasses.