| All-solid-state laser have many advantages like stable,the good quality of light beam,reliable and high transformation efficiency.Recent years,yellow laser is widely used in many fields,such as medical treatment,atomic cooling and trapping,as well as communication.Compare to the traditional yellow lasers,diode laser pump Dy ions doped gain medium have smaller volume and better stability without the nonlinear frequency conversion.The doped concentration of high degree of disordered Na2Gd4?MoO4?7 can highly doped rare earth ions,thus,the absorption and emission spectra bandwidth would broadened.The article study on the growth of Na2Gd4?MoO4?7 doped with Dy,Tb or Eu ions,and the thermal and spectral characteristic.The study and result of this article as follows:1?The polycrystalline material was synthesized by solid-state reaction and successfully grow the Na2Gd4?MoO4?7 crystal doped with Dy,Tb or Eu ions by the Czochralski method.2?Thermal properties were measured by Thermo-differential thermal scanning analyzer,and we obtained that the melt point is 1179°C,heating above the melting point,the sample would decompose,generate to Gd2?MoO4?3 and Na2MoO4.3?The intensity parameter of Dy:Na2Gd4?MoO4?7 were calculated to?2=20.89×10-2020 cm2,?4=4.11×10-2020 cm2,?6=2.32×10-2020 cm2 base on the Judd-Ofelt theory,the transition 4F9/2?6H13/2?575 nm?has the highest branching ratio?74.5%?,the emission cross-section ofis1.05×10-2020 cm2,the radiative lifetime of 4F9/2/2 level was 142?s and the quantum efficiency was75.9%.Compared to other Dy doped crystal,such as LiNbO3,Lu2SiO5 et al,Dy:Na2Gd4?MoO4?7have the higher branching ratio and emission cross-section in the transition 4F9/2?6H13/2?575nm?.4?Dy:Na2Gd4?MoO4?7 was codoped with the Tb ions,make the Dy/Tb:Na2Gd4?MoO4?7 crystal has the higher branching ratio?80.2%?of the transition 4F9/2?6H13/2,and higher emission cross-section?1.34×10-2020 cm2?.It was also demonstrated that the codoping of Tb3+depopulates the population of the laser lower level Dy3+:6H13/2,and has little influence on the laser upper level Dy3+:4F9/2/2 at the same time,which is benefited to the possible population inversion for the Dy3+:4F9/2?6H13/23/2 transition,and enhances the fluorescence emission.5?At last,we grew codoped Eu ions in Dy:Na2Gd4?MoO4?7.Compared to the Dy:Na2Gd4?MoO4?7,the Dy/Eu:Na2Gd4?MoO4?7 crystal has the higher branching ratio?80.0%?of the transition 4F9/2?6H13/2,and higher emission cross-section?1.55×10-2020 cm2?and higher quantum efficiency?57.4%?. |
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