Phonon-Assisted Population Inversion in Lanthanide-Doped Upconversion Ba<sub>2</sub> LaF<sub>7</sub> Nanocrystals in Glass-Ceramics.

Xu, Xuhui; Zhang, Wenfei; Yang, Decheng; Lu, Wei; Qiu, Jianbei; Yu, Siu Fung · Adv Mater · 2016

basic_science · Level V

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Abstract

The effective population inversion of <sup>2</sup> H<sub>11/2</sub> from <sup>4</sup> S<sub>3/2</sub> state of Er<sup>3</sup><sup>+</sup> ions can be achieved through the annihilation of phonons; random lasing action from BLF films embedded with Yb<sup>3+</sup> /Er<sup>3+</sup> codoped BLF nanocrystals is demonstrated and high ambient temperature (>433 K) operation lasers with a very low excitation threshold (<530 nJ cm<sup>-2</sup> ) are realized.