Growth And Properties Of Dysprosium Doped Yttrium Aluminate And Samarium And Samarium Cerium Co-doped Gadolinium Yttrium Aluminate Laser Crystal

Yellow-orange lasers?wavelength range 577-620nm?are widely used in lidar,biomedical detection,military detection,astronomy and other aspects.In particular,display lighting has an important role in the diagnosis and treatment of ophthalmology.Compared with lasers of other wavelengths,lasers in the yellow light band have their irreplaceable advantages.At present,there are two main methods to obtain yellow light lasers:sum frequency and stimulated Raman scattering?SRS?effect.However,the multi-cavity system used in yellow orange light lasers is still very complicated and inefficient.The lack of a suitable active medium still limits the development of all new compact solid state yellow-orange laser light sources.Therefore,it is necessary to develop a laser material capable of directly emitting yellow-orange light.The laser gain matrix is an important part of the laser.To achieve laser operation,it needs to have a wide emission spectrum,high thermal conductivity,and high emission cross section.In the study of new materials,Gd³⁺ions were doped into YAP laser crystals to form a new mixed crystal GYAP crystal.This new type of disordered mixed crystal has a large ground state split,many types of substitution sites,and a disordered structure,which can make the absorption spectrum and fluorescence spectrum of the doped activated ions non-uniformly broaden,which is conducive to the operation of the laser.In this paper,Dy:YAP?Sm:GYAP and Sm/Ce:GYAP crystals are used as research objects,and their growth processes and spectral properties are studied in detail.The possibility of Sm/Ce:GYAP crystal as a yellow-orange laser crystal was evaluated.The main contents and achievements of this paper are as follows:1.The first chapter introduces the current status of the development of yellow-orange lasers,briefly describes the implementation methods of yellow-orange lasers,the advantages and disadvantages of some common solid gain media that produce yellow-orange light,and proposes yellow-doped erbium-doped cerium-doped cerium The necessity of the research on orange solid gain materials points out the basis for selecting GYAP crystals as the research object in this paper.2.Introduced the growth principle and technology of GYAP crystals in detail,and used Al₂O₃,Y₂O₃,Gd₂O₃with purity of 99.999%as raw materials,and successfully grown high-quality GYAP single crystals by the pulling method;XRD of the grown GYAP crystal structure According to test characterization,its crystal structure is the same as the YAP crystal structure,the space group is also Pnma,the unit cell parameters are a=5.321???,b=7.164???,and c=5.407???,and no structural phase change occurs during the entire process.3.The Dy:YAP crystal was prepared by the J.Czochralski method,and the XRD structure,absorption spectrum,excitation spectrum and emission spectrum of the crystal were characterized.The XRD pattern test of the Dy:YAP crystal was carried out,which matched with the YAP standard PDF card.The results show that the Dy:YAP crystal has th e same structure as the card,is an orthogonal crystal system,the space group is Pnma,and the cell parameter is a=5.316???,B=7.378???,c=5.172???.The JO intensity parameter and fluorescence branching ratio of Dy:YAP crystal are calculated by Judd-Ofelt theory.The JO intensity parameter of Dy:YAP crystal is?2=2.74×10^-20cm²,?4=1.24×10^-20cm²,?6=2.99×10^-20cm².The fluorescence spectrum of Dy:YAP crystal was tested,and the emission intensity of Dy:YAP crystal at 580nm was the largest.The maximum emission cross section of the emission peak at 580nm is0.350×10^-20cm²,and the fluorescence quantum efficiency of the Dy:YAP crystal at ⁴F_9/6?⁶H_13/2transition is 22.9%.The corresponding ⁴F_9/6 level life of Dy:YAP crystal is 170us.4.Sm:GYAP and Sm/Ce:GYAP crystals were successfully grown by the J.Czochralski method.The absorption spectra of the crystals were studied.The JO intensity parameters,fluorescence lifetime,and spontaneous emission of Sm/Ce:GYAP crystals were analyzed by Judd-Ofelt theory.The JO strength parameters of Sm/Ce:GYAP crystal are?₂=2.02×10^-20cm²,?₄=2.82×10^-20cm²,?₆=4.88×10^-20cm².The excitation and emission spectra of Sm:GYAP and Sm/Ce:GYAP crystals were tested.The emission intensity of Sm/Ce:GYAP crystal at 602 nm is at least four times that of Sm:GYAP crystal.The maximum emission cross section of the emission peak at 602 nm is 5.01×10^-20cm²,which is larger than the maximum emission cross section of Sm³⁺single-doped GYAP crystal,which is 1.6×10^-20cm².The fluorescence branch ratio of the Sm/Ce:GYAP crystal at the ⁴G_5/2?⁶H_7/2transition is 48.9%,which is greater than43.1%of the Sm:GYAP crystal.The corresponding ⁴G_5/2 energy level lifetimes of Sm:GYAP and Sm/Ce:GYAP crystals are 298us and 305us,respectively.