The Study Of Crystal Growth And Spectroscopic Properties Of Rare Earth Ions Activated CaYalO₄ And SrLaGaO₄ Disordered Laser Crystals

The development of new laser crystals has always been a hot topic in laser material research.Among them,the～3μm mid-infrared laser has great application prospects in medical fields such as laser surgery due to its strong absorption of water molecules.Ultrafast laser is widely used in intelligent processing,communication and remote sensing,national defense and military,medical cosmetology and scientific research because of its advantages such as large pulse energy,high peak power and short duration.ABCO₄ system is a kind of excellent laser crystal matrix materials.Due to its low phonon energy and disordered structure,it shows great advantages in～3μm mid-infrared laser and ultrafast laser materials.In this paper,a series of CaYAlO₄～3μm mid-infrared laser crystals activated by Ho³⁺and a new type of ultrafast laser gain material Sr La Ga O₄were developed,and the spectroscopic properties of crystals were systematically studied.The main work is as follows:Firstly,CaYAlO₄ crystal activated by Ho³⁺ions was grown by Czochralski method,and its spectroscopic properties were systematically analyzed by J-O theory.A series of Ho³⁺:CaYAlO₄ crystals co-doped with sensitizing ions Nd³⁺,Yb³⁺and deactivating ions Pr³⁺,Sm³⁺were designed to overcome the problems of lack of commercial pump source and the self-termination effect of～3μm laser.The results show that Yb³⁺is an effective sensitizing ion with an energy transfer efficiency of 83.5%at 980 nm.Nd³⁺doping not only sensitized,but also plays a deactivation role.Under the excitation of 808 nm,the lifetimes of the upper and lower levels of～3μm laser are 0.240 and 0.723 ms,respectively,which effectively inhibits the self-termination effect.The Pr³⁺and Sm³⁺deactivated Yb³⁺/Ho³⁺:CaYAlO₄ tridoped crystals show enhanced～3μm spectroscopic emission,and the upper and lower energy level lifetimes of～3μm laser are 0.154 ms,0.298 ms(Pr³⁺)and 0.114 ms,0.395 ms(Sm³⁺),respectively,which proves that they have good deactivation effect.Therefore,through optimized design,Nd³⁺/Ho³⁺:CaYAlO₄,Yb³⁺/Ho³⁺/Sm³⁺:CaYAlO₄,Yb³⁺/Ho³⁺/Pr³⁺:CaYAlO₄ crystals can be used as potential mid-infrared laser gain materials,and are expected to realize～3μm mid-infrared laser output.Secondly,In the Ga-rich composition,Sr La Ga O₄ crystal was successfully grown by Czochralski method,and its structure and refractive index equation were studied.Nd³⁺:Sr La Ga O₄ and Dy³⁺:Sr La Ga O₄ crystals were grown by Czochralski method,and their absorption spectra,fluorescence emission spectra and lifetime decay curves were measured at room temperature.The relevant spectroscopic parameters were calculated based on J-O theory.The emission cross sections of Nd³⁺:Sr La Ga O₄ crystal at 1.0μm are 4.14×10^-20 cm²[π]and4.12×10^-20 cm²[σ],and the FWHM are 8.00 nm[π]and 19.47 nm[σ].The large non-uniform spectroscopic broadening indicates that the crystal has good performance in ultrafast laser and tunable laser fields.The FWHM of Dy³⁺:Sr La Ga O₄ crystal in the yellow wavelength band is13.58 nm and the yellow lifetime is 0.294 ms.Meanwhile,a strong emission band appears at2.94μm with a FWHM of 342 nm and the mid-infrared lifetime is 0.130 ms.The research suggests that Dy³⁺:Sr La Ga O₄ crystals can be used as potential ultrafast or tunable laser crystal material in yellow and mid-infrared band.