Fabrication Of Yb:SrF₂ Transparent Ceramics And Research Of Its Spectrum Properties

Laser technology plays a crucial role in various fields such as economy,military,information,medical care,industry,business,environment and high-end manufacturing,and is regarded as one of the 18 major key technologies affecting the future development of the world.Laser gain media is the foundation and core of laser technology development,and its quality directly determines the performance of laser.Transparent ceramics are a kind of laser gain dielectric materials with simple preparation process,low cost,controllable shape and suitable for mass production.SrF₂transparent ceramics are suitable as the matrix material for laser work due to the advantages of low phonon energy,low refractive index,wide transmittance range,no birefringence effect and short preparation period.Yb³⁺ion is a commonly used active ion in solid state lasers due to its advantages of simple electron level structure,wide absorption spectrum and emission spectrum,long fluorescence life,low quantum defect and small ion radius.In this paper,Yb:SrF₂ nanometer powders with different Yb³⁺ion doping concentrations were synthesized by chemical precipitation method,and the corresponding transparent ceramic samples were prepared by vacuum hot-pressing sintering method.The influence of Yb³⁺ion doping on the spectral properties of powders and ceramic samples was systematically studied.The main research contents are as follows:1.Yb:SrF₂ nanometer powder was synthesized by chemical coprecipitation.The influences of titration sequence,titration speed,reaction concentration and Yb³⁺ion doping concentration on the grain size,cell parameters and micromorphology of the powder were systematically studied.The optimal synthesis parameter conditions were obtained:under the process condition of anion titration adding cations at a slow speed and reaction concentration of 1mol/L,Yb:SrF₂ nano-powder with uniform particle size distribution,light degree of agglomeration,more regular morphology and high sintering activity could be synthesized with an average particle size of about 30 nm.As the doping concentration of Yb³⁺increased from 1 at.%to 5 at.%,the average grain size decreased from 16 nm to 10 nm,and the lattice constant increased from 5.790?to 5.808?.2.The above powder was prepared by vacuum hot pressing sintering,Yb:SrF₂transparent ceramics,the effects of sintering temperature,holding time,Yb³⁺ions doped effect on ceramic microstructure and the optical transmittance,the results show that the sintering temperature is 800?,holding time for 2h under the technological conditions of preparation of high quality of transparent ceramics,optical transmittance was 88%at 1200 nm,the average grain size of 400 nm.3.The spectral properties of different Yb³⁺ion doped SrF₂ ceramics were studied.The results show that the maximum absorption cross section of Yb:SrF₂ceramics at 974 nm reaches 0.87×10^-20 cm²,and the absorption half-height width FWHM of the absorption peak reaches 30 nm,which is higher than tha of Yb:Ca F₂ceramic(22nm).With the increase of Yb³⁺ion doping concentration,the distortion inside the lattice increases,which reduces the local symmetry around the optical center of Yb³⁺,increases the fluorescence intensity,and shortens the fluorescence life.The doping concentration was 1 at.%Yb:the fluorescence life of SrF₂ ceramics reached4.58ms,which is higher than the lifetime of Yb:Ca F₂(2.4ms),which is conducive to energy storage.Research shows that Yb:SrF₂ transparent ceramics are the ideal choice for 980 nm LD pumped solid-state lasers.They have great advantages in realizing mode-locked laser output and are very suitable for high-power laser output.