Bulk Crystal Growth, First-Principles Calculations, and Mid-Infrared Spectral Properties of Dy³⁺ Doped and Dy³⁺/Nd³⁺ Codoped LaF₃ Single Crystals

Dy 3+ doped and Dy 3+ /Nd 3+ codoped LaF 3 single crystals were successfully grown by the Bridgman-Stockbarger method in a self-made medium frequency furnace. The crystal structures of LaF 3 were investigated, and their geometry optimizations were carried out. The electronic structures including band structure and density of state were calculated by using first-principles calculations based on density functional theory. The polarized absorption and emission spectra including near-infrared and mid-infrared fluorescence spectra were measured at room temperature. The energy transfer mechanism from Nd 3+ ion to Dy 3+ ion was presented, and the microscopic transfer parameters were calculated based on the phonon-assisted energy transfer theory. In summary, two promising routes of Dy 3+ /LaF 3 crystal pumped by 1280 nm LD and Dy 3+ /Nd 3+ /LaF 3 crystal pumped by 790 nm LD were proposed for a mid-infrared laser.