Growth,first-principles simulations and near-infrared optical properties of rare earth (Nd3+, Er3+)-doped CeF3 crystals for laser applications

Nd³⁺:CeF₃ and Er³⁺:CeF₃ crystals with different doping concentrations were successfully grown by the Bridgman method. The physicochemical parameters, such as crystal structure and phonon vibration energy were obtained by XRD and Raman tests. The results show that rare earth (Nd³⁺ or Er³⁺) does not change the hexagonal phase structure of the crystal, and the doping of rare earth ions does not change the maximum phonon frequency. The measured results are 388 and 392 cm^??1, respectively, which are similar to CeF₃ single crystal and half of common oxide crystal. According to the first principle, the difference charge density of the two crystals can be intuitively obtained. The calculated band gap values of the two crystals are 2.91 and 4.37 eV, respectively, which are similar to the results of absorption spectrum measurement. The NIR luminescence performance of Nd³⁺:CeF₃ crystal was tested by 808 nm pump. When the doping concentration reached 2 at%, the emission intensity was the strongest at 1064 nm (⁴F_3/2→⁴I_11/2). The luminescence properties of Er³⁺:CeF₃ crystal at 1550 nm (⁴I_13/2→⁴I_15/2) were tested by 980 nm pump. The emission intensity keeps the highest when the doping concentration reaches 3 at%. The concentration quenching and the dipole-dipole interaction in crystals are studied using energy transfer theory, and the J-O strength parameters of crystals are calculated. The results show that Nd³⁺:CeF₃ and Er³⁺:CeF₃ crystals have excellent properties and excellent near-infrared luminescence performance, which has great potential in laser applications.