Rare Earth Ion Doped Phosphate Crystal Growth, Phosphor Preparation And Luminescence Performance Research

Rare-earth phosphate is an important matrix material with excellent chemical stability and thermal stability,no temperature quenching even at high temperatures,and due to its unique structure,rare earth phosphate can be doped with rare earth ions at high concentration without causing lattice structure distortion.In this paper,lead pyrophosphate（Pb₂P₂O₇）was used as a flux,and the Yb:YPO₄single crystal with a maximum size of about 12.5×4.5×0.2 mm³ was grown by a high temperature solution method.High efficiency continuous-wave（CW）laser operation was realized by using a parallel planar resonant cavity with a length of 2 mm.The maximum output power,slope efficiency and optical-to-optical efficiency of CW laser were measured to be 1.71 W,44.3%and 39.6%respectively under the condition that the optimal output coupling transmittance was 1%.Using two-dimensional material MoS₂ as saturable absorber,passively Q-switched pulse output was realized for the first time in a 4 mm parallel planar resonant cavity.Under the condition of the output coupling transmittance T=5%,the output power of the pulse laser was 0.29 W,the slope efficiency was 11.2%,and the pulse repetition frequency was 856 kHz.The pulse energy,pulse width and peak power of the passively Q-switched pulsed laser were measured to be 0.33μJ,77 ns,and 4.29 W,respectively.Gd（P_yV1-_y）O₄:x at.%Tm³⁺（x=1,2,3,4 and 5;y=0,0.1,0.3,0.5,0.7,0.9 and 1）phosphors were synthesized by chemical coprecipitate.When the matrix material is pure GdPO₄（y=1）,the phosphors exhibit a monoclinic phase.When the ratio of VO₄^3-to PO₄^3-is 1:9（y=0.9）,an impurity phase begins to appear.When the ratio of VO₄^3-to PO₄^3-exceeds 3:7（y≤0.7）,the sample shows a tetragonal structure.According to the intensity of the emission spectrum and the color purity of the luminescence,the optimal doping ratio of VO₄^3-to PO₄^3-was determined to be 1:9.With Gd(P_0.1V_0.9)O₄ as the matrix,the influence of different concentrations of Tm³⁺on the luminescence performance of phosphor powder was continuously explored,and the optimal doping concentration of Tm³⁺was x=2.The quenching mechanism of concentration was studied as dipole-dipole interaction.A series of K₃Gd（PO₄）₂:x at.%Eu³⁺,y at.%Bi³⁺（x=1,2,3,4,5,6 and 7;y=2,4,6,8,10 and 20）phosphors were prepared by high temperature solid-state method.Eu:K₃Gd（PO₄）₂ phosphors have the same monoclinic structure as K₃Gd（PO₄）₂.In K₃Gd（PO₄）₂matrix,the magnetic dipole transition emission of Eu³⁺ions dominates,and the optimal doping concentration is 6 at.%.The doping of Bi³⁺ions increases the intensity and range of the excitation spectrum,but the luminescent intensity decreases somewhat.The luminescent color of the phosphors can be tuned to change from orange red to white by adjusting the doping ratio of Bi³⁺and Eu³⁺ions.