The Study Of Crystal Growth And Spectral Properties Of Er³⁺Activated SrLaGa₃O₇ Mid-Infrared Laser Crystals

SrLaGa3O7 crystal is chosen as host crystal in this paper.SrLaGa3O7 crystal belongs to one member of tetragonal system ABC3O7(-A=Ca,Sr,Ba;B= Y,La,Gd;C=Al,Ga-),with partly disordered melilite structure,with good physicochemical properties and low phonon energy,and since it melts congruently,high-quality bulk single crystal of it can be grown by Czochralski method.All these make SrLaGa3O7 crystal become an excellent host crystal of mid-infrared laser.Er ions is selected for activating ions and the spectral properties of Er3+activated SrLaGa3O7 laser crystals is studied.First,the SrLaGa3O7 polycrystals is compounded by solid phase sintering methods.The crystal growth technology is studied.SrLaGa3O7 crystals including different Er ions concentration and different co-doping ions types were grown by Czochralski technique.There are five types of doping of SrLaGa3O7 crystals,such as Er:SrLaGa307,Er,Eu:SrLaGa3O7,Er,Nd:SrLaGa3O7,Yb,Er:SrLaGa3O7 and Yb,Er,Pr:SrLaGa30O7crystals.In addition,the crystal phase characterizations were measured and analyzed.The crystallographic axes were determined by the X-ray crystal orientation instrument.The rare earth concentrations were measured by the inductively coupled plasma-atomic emission spectroscopy(ICP-AES)method,and then the effective segregation coefficients of rare earth ions in the above crystals were calculated.Then,at room temperature,the spectroscopic properties were measured and studied.The Judd-Ofelt theory was used to study the absorption spectroscopic characteristics of Er:SrLaGa3O7 single crystals,and the values of a serial of very important parameters are presented.The influences of Er ion dopant concentrations on the optical properties has been analyzed in detail.As for the co-doped and triply-doped Er:SrLaGa3O7 crystals,the effects of the sensitive ions(Yb3+,Nd3+)and deactive ions(Eu3+,Pr3+)co-doped SrLaGa3O7 crystals on the optical properties and spectral parameters were compared and analyzed.In summary,there is a absorption band with peak at 980 nm in Er3+:SrLaGa3O7 crystal with width at half maximum of 28 nm matches the commercial 980 nm InGaAs laser diodes.After co-doping Eu and Pr ions,the NIR fluorescence emission was decreased and the self-termination effect was inhibited,so the 2.7μm MIR fluorescence emission was improved in Er:SrLaGa3O7 crystals.When the Yb ions was codoped in Er3+:SrLaGa3O7 crystal,there is a enhanced absorption band with peak at 980 nm and it can improve the absorption of the pump energy of 980 nm InGaAs laser diodes.But it cannot inhibit the competitive luminescence and self-saturation bottlenecks effect.Nd ions can not only increase to 808 nm absorption of the pump energy,but also can inhibit the competitive luminescence and self-saturation bottlenecks effect.Yb ions can improve the absorption of pump energy by the energy transition of Yb3+:4F5/2 levels to Er3+:4I11/2 levels in Er3+/Yb3+/Pr3+:SrLaGa3O7 crystal.The lifetime of lower level 4I13/2 decreases significantly due to the Pr3+ ions,so the self-termination for 2.7 μm laser is inhibited.At the same time,the near-infrared and up-conversion emission is decreased,also the mid-infrared emission is enhanced in Er3+/Yb3+/Pr3+:SrLaGa3O7 crystal.In addition,we also studied the rate equation and the energy transfer simply.To sum up,a serial of erbium-activated,Eu3+,Yb3+,Pr3+ and Nd3+ codoped SrLaGa3O7 crystals were grown for the first time,and through the systemic researches of this thesis make us conclude that Er3+/Eu3+:SrLaGa3O7,Er3+/Nd3+:SrLaGa3O7 and Er3+/Yb3+/Pr3+:SrLaGa3O7 crystals are good candidates for LD pumped 2.7 pm mid-infrared laser.