| Summary: | An efficient enhancement of 2.78 μm emission from the transition of Er<sup>3+</sup>: <sup>4</sup>I<sub>11/2</sub> → <sup>4</sup>I<sub>13/2</sub> by Tm<sup>3+</sup> introduction in the Er/Tm: PbF<sub>2</sub> crystal was grown by the Bridgman technique for the first time. The spectroscopic properties, energy transfer mechanism, and first-principles calculations of as-grown crystals were investigated in detail. The co-doped Tm<sup>3+</sup> ion can offer an appropriate sensitization and deactivation effect for Er<sup>3+</sup> ion at the same time in PbF<sub>2</sub> crystal under the pump of conventional 800 nm laser diodes (LDs). With the introduction of Tm<sup>3+</sup> ion into the Er<sup>3+</sup>: PbF<sub>2</sub> crystal, the Er/Tm: PbF<sub>2</sub> crystal exhibited an enhancing 2.78 μm mid-infrared (MIR) emission. Furthermore, the cyclic energy transfer mechanism that contains several energy transfer processes and cross-relaxation processes was proposed, which would well achieve the population inversion between the Er<sup>3+</sup>: <sup>4</sup>I<sub>11/2</sub> and Er<sup>3+</sup>: <sup>4</sup>I<sub>13/2</sub> levels. First-principles calculations were performed to find that good performance originates from the uniform distribution of Er<sup>3+</sup> and Tm<sup>3+</sup> ions in PbF<sub>2</sub> crystal. This work will provide an avenue to design MIR laser materials with good performance.
|
|---|