The Growth And Properties Of Rare-earth Ions Doped La₂CaB₁₀O₁₉ Crystals

La₂Ca B₁₀O₁₉（LCB）crystal is a promising nonlinear optical crystal with good nonlinear optical properties,moderate birefringence,high UV transmittance and laser damage threshold,stable physical and chemical properties,and nonhygroscopic.Moreover,the La³⁺ions in LCB crystal can be an potential laser crystal after substituted by other rare earth（RE）ions,leading to self-frequency doubling output.Previous studies mainly focused on the growth and optical properties of RE-doped LCB crystals,such as Nd³⁺and Yb³⁺etc.,whose output wavelengths are in the near infrared range.The invention and commercial application of In Ga N/Ga N-laser diodes have made it feasible to directly obtain the visible lasing radiation by pumping rare earth（RE）doped laser crystals,which has great potential application for all solid-state lasers.Therefore,it is important to study the growth and spectral properties of Eu³⁺-doped LCB crystals.This paper mainly focuses on the growth,optical and thermal properties of Eu³⁺-doped LCB crystals.It mainly includes:1.The parameters for the crystal growth were optimized in this work.The ideal temperature gradient was achieved by control the program temperature difference of each section in the three-stage growth furnace.By adjusting the rotation mode of seed crystal,the high-quality RE-doped LCB crystals were grown.Compared with the grown pure LCB crystal,the thickness along the c direction of RE-doped LCB crystals are significantly increased.2.Eu³⁺:LCB crystals with nominal doping concentrations of 3%,7%and 10%were successfully grown,and the maximum weight is 49.67 g.The absorption and emission spectra of Eu³⁺:LCB crystals were obtained at room temperature.The spectral properties of Eu³⁺:LCB crystals were calculated by Judd-Ofelt theory for the first time.It was found that Eu³⁺:LCB crystals with the nominal ration of 7%had the best optical properties.Their absorption cross section,spectral line intensity,emission cross section and quantum efficiency are 3.197×10^-20cm²,7.97×10^-22cm²,1.55×10^-20cm²,77%,respectively.Compared with other Eu³⁺-doped laser crystals,Eu³⁺:LCB crystals have better spectral performance,which make it possible to realize visible laser output by pumped with laser diodes at 395 nm or 464 nm.Thus,the Eu³⁺:LCB crystals may have promising application for all solid-state lasers.Moreover,through the spectral studies of emission spectrum of Eu³⁺:LCB crystals with various ratios,the occupation sites of the substituted RE are studied.It is found that the Eu³⁺ions replace the La³⁺atoms at first.With increasing the Eu³⁺ions doping concentration,they will occupy both the La³⁺and Ca²⁺sites,which gives well explanation to dual-frequency laser produced in Nd³⁺:LCB and Yb³⁺:LCB crystals.3.Sm³⁺and Eu³⁺co-doped La₂Ca B₁₀O₁₉(Sm³⁺:Eu³⁺:LCB)crystal with the nominal ratios of 4%and 7%respectively has been successfully grown.The emission spectrum of Sm³⁺:Eu³⁺:LCB crystal excited at 474 nm was measured,which demonstrates that energy transfer between Sm³⁺and Eu³⁺ions in the Sm³⁺:Eu³⁺:LCB crystal.The emission intensity of Sm³⁺:Eu³⁺:LCB crystal is about 2 times stronger than that of Eu³⁺:LCB crystal,indicating that Sm³⁺:Eu³⁺:LCB crystal could be a promising visible laser candidate.The effective energy transfer in Sm³⁺:Eu³⁺:LCB crystal enhances absorption intensity and emission intensity of Eu³⁺ions,and further improved application potential in laser fields.4.Ce³⁺doped La₂Ca B₁₀O₁₉(Ce³⁺:LCB)crystal with the nominal ratio of 3%has been successfully grown.The absorption,excitation-emission spectrum and thermal performance at high temperature of Ce³⁺:LCB crystal were obtained.The results demonstrate that Ce³⁺:LCB crystal has excellent optical properties and good thermal stability,which is conducive to its application for lasers.5.By adjusting the ratio of crystal ingredients and sintering temperature,Yb³⁺:LCB crystals with the nominal ratios of 10%and 20%were successfully grown.It was found that the grown crystals are not so easy to crack.Furthermore,the absorption and emission of Yb³⁺:LCB crystals spectra were studied at room temperature.