Enhancement of 1.8 μm emission in Er3+/Tm3+ co-doped tellurite glasses: Role of energy transfer and dual wavelength pumping schemes

Abstract

Thulium (Tm3+) and erbium (Er3+)-doped tellurite glasses were synthesized and explored their spectroscopic properties for optical amplification and medical appliances. The emission at 1.8 μm of Tm3+ ions has been enhanced significantly in Er3+/Tm3+ co-doped tellurite glasses under dual pumping lasers at 808 and 980 nm. Emission cross-section of the Tm3+ ions is found to be 3.46 × 10−20 cm2 which was evaluated by utilizing the Mc-Cumber theory. The possible energy transfer mechanisms between Er3+ and Tm3+ ions under 808 and 980 nm excitations were investigated by utilizing the excitation, emission and decay curve analyses. Effect of dual wavelength pumping on the 1.5 and 1.8 μm spectral profiles is also enlightened. Decay curves of Tm3+:3H4 → 3F4 (1440 nm) transition and Er3+: 4I13/2 → 4I15/2 (1531 nm) transition in the Tm3+ singly and Er3+/Tm3+ co-doped tellurite glasses have been analyzed under 808 nm laser excitation. Energy transfer efficiency is evaluated between Er3+: 4I13/2 and Tm3+:3F4 states from the decay curves and it is found to be 83%. The results are significant and indicating that the Er3+/Tm3+ co-doped tellurite glasses could be a potential candidate for optical fiber amplification at around 1.8 μm region under dual wavelength pumping scheme.