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

摘要

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 mu m 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 x 10(-20) cm(2) 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 mu m spectral profiles is also enlightened. Decay curves of Tm3+:H-3(4) -> F-3(4) (1440 nm) transition and Er3+: I-4(13/2) -> I-4(15/2) (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+: I-4(13/2) and Tm3+:F-3(4) 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 mu m region under dual wavelength pumping scheme. (C) 2020 Elsevier B.V. All rights reserved.