White light emission from Dy3+-doped LiLuF4 single crystal grown by Bridgman method

Lithium lutetium fluoride (LiLuF₄) single crystals doped with different Dy³⁺ ion concentrations were grown by Bridgman method. The Judd-Ofelt (J-O) strength parameters (Ω ₂, Ω ₄, Ω ₆) of Dy³⁺ in LiLuF₄ crystal are calculated according to the measured absorption spectra and the J-O theory, by which the asymmetry of the Dy³⁺:LiLuF₄ single crystal and the possibility of attaining stimulated emission from ⁴F_9/2 level are analyzed. The capability of the Dy³⁺:LiLuF₄ crystal in generating white light by simultaneous blue and yellow emissions under excitation with ultraviolet light is produced. The effects of excitation wavelength and doping concentration on chromaticity coordinates and photoluminescence intensity are also investigated. Favorable CIE coordinates, x=0.319 3 and y=0.349 3, can be obtained for Dy³⁺ ion in 2.701% molar doping concentration under excitation of 350 nm.