Growth And Properties Of Tm³⁺:BSO And Ho³⁺:BSO Laser Crystals

The development of laser has a perfect research system,in which 2μm band laser has been widely concerned in medical,radar,material processing and other fields.Tm and Ho ions are common rare earth ions to achieve 2μm laser output.This paper mainly studies the growth,structural analysis and spectral properties of Tm³⁺:BSO crystals and Ho³⁺:BSO crystals.The following research results were achieved in the thesis.1.Tm³⁺:BSO crystal growth and performance study.The Tm³⁺:BSO crystals with the size ofΦ25 mm×100 mm were grown by the crucible descending method.XRD results show that doping does not change the crystal structure.The FWHM value obtained by XRC test is 19",which indicates that the crystal has good crystal quality and structural integrity.The content of Tm³⁺in BSO crystals was determined by ICP-OES method,and the effective separation coefficient of Tm³⁺:BSO was 0.41.The spectral properties were investigated based on absorption and luminescence spectra.The J-O intensity parameters（Ω₂,Ω₄ andΩ₆）,fluorescence branching ratio,radiation lifetime and spontaneous emission probability were calculated by Judd-Ofelt（J-O）theory.The absorption and emission spectra of Tm³⁺:BSO crystal at 2μm transition were measured and the gain cross section spectra were calculated.The fluorescence attenuation curve was measured and the fluorescence attenuation kinetics of ³F₄level was analyzed.2.Ho³⁺:BSO crystal growth and performance study.The Ho³⁺:BSO crystals with the size ofΦ25 mm×100 mm were grown by the crucible descending method.XRD results show that doping does not change the crystal structure.The FWHM value obtained by XRC test is 16",which indicates that the crystal has good crystal quality and structural integrity.The content of Ho³⁺in BSO crystals was determined by ICP-OES method,and the effective separation coefficient of Ho³⁺:BSO was 0.37.Based on the absorption spectrum and emission spectrum of the grown crystal,the gain cross-section spectrum is calculated.The spectral characteristics of 2μm laser manipulation are studied by ⁵I₇→⁵I₈ transition.J-O intensity parameters（Ω₂,Ω₄andΩ₆）,spontaneous emission probability,fluorescence branching ratio and radiation lifetime were calculated using Judd-Ofelt（J-O）theory.The fluorescence attenuation curve was measured and the fluorescence attenuation kinetics of ⁵I₇ energy level was analyzed.Finally,the paper summarizes the work.BSO crystal has the advantages of low melting point,mature growth technology,high transmittance,good heat transfer performance and large dose doping,so it is an important matrix material for laser crystal.Tm:BSO crystals can be used to make tunable lasers with tuning ranges over 200 nm.Ho:BSO crystal has a wide absorption band and is also a potential eye-safe 2μm laser material.Some suggestions are given to the problems existing in the experiment and to be studied.