Spectroscopy and energy transfer dynamics of Nd3+ strengthened Er3+: 2.7 μm emission in modified fluoride glass

- A modified fluoride glass with Tg=453 °C and Txonset-Tg=138 °C.
- A rare Nd3+:4I15/2 absorption band around 1600 nm that never been reported to induce high ET efficiency with Er3+:4I13/2 level.
- Surprisingly, spectroscopic process based on Nd3+:4I15/2 level is found.
- Nd3+ strengthens the Er3+: 2.7 μm emission 12,144 times.

A modified fluoride glass with high Tg (453 °C) and Txonset-Tg(138 °C) value was studied as the Er3+:Nd3+ codoped 2.7 µm gain media. Interestingly, Nd3+: 1600 nm absorption band that never been reported in glass material was observed. This band induces efficient non-phonon-assisted de-sensitization process in Er3+: 2.7 µm emission. Surprisingly, a strong 817 nm peak was detected, which is proved to be induced by the cross-relaxation process based on the Nd3+:4I15/2 level, making the energy back-transfer from Nd3+ to Er3+ possible. Results show that Nd3+ strengthens the Er3+: 2.7 µm emission significantly, but energy transfer coefficient from Er3+ to Nd3+ increases greatly with Nd3+ enhancement, leading to more complicated inter-ionic interactions and more energy loss. Low Nd3+:Er3+ ratio is preferred to achieve strong 2.7 µm emission, meanwhile, suppressing upconversion luminescence, weakening the Nd3+ interactions and decreasing the thermal load of 2.7 µm lasing effectively.