The Study On2~3μm Mid-infrared Luminescence Properties Of Rare-earth Doped Oxyfluoride Glass

Mid-infrared lasers operating in2~3μm wavelength region, where water exhibitsintense absorption, have enormous potential applications in civil and military fileds. It’s thebasic content of the research for2~3μm fiber lasers to explore glass gain medium with goodoptical properties and practical value. Nowadays, the relative research on glass materials,especially for the emissionabout3μm, has been focused on fluoride and chalcogenide glasses,which have a low phonon energy. However, fluoride and chalcogenide glasses featurecongenital defects in the chemical and mechanical stability, which is difficult to overcome inpractical applications. Oxyfluoride glasses combine excellent advantages of fluoride glassesin optical properties and oxide glasses in mechanical properties, and thus become ideal opticalmaterials for mid-infrared lasers. This paper aims to enchance the mid-infrared fluorescenceof Er3+and Ho3+in oxyfluoride glasses by reducing the hydroxyl content and introducingsensitizer ions.This dissertation is composed of five chapters. The first chapter provides an overview ofrequirements of glass matrix for mid-infrared lasers, and reviews the related research progress.The second chapter briefly describes the experimental methods and equipments involved,meanwhile, the main calculating theories about rare earth spectroscopy is provided includingJudd-Ofelt theory, absorption and emission cross section, energy transfer coefficients and etc.The experimental part of this dissertation is mainly about studying the fluorescence ofEr3+:2.7μm in oxyfluoride tellurite glasses (TeO2-ZnO-ZnF2) and Ho3+:2.0μm,2.9μm inoxyfluoride germanate glasses (50GeO2-20Al2O3-15LaF3-15LiF). The specific contents are asfollows:In the third chapter, a dry technique combining the addition of fluoride with shieldinggas (O2or Ar) has been exploited to remove OH－and enhance the mid-infrared emission inTeO2-ZnO-ZnF2glass system. The dehydrating results were evaluated based on the Fouriertransform infrared transmission spectra. Furthermore, the influence of ZnF2content and/orshielding gas on the physical and spectroscopic properties of Er3+-doped samples has beeninvestigated in detail. In the fourth chapter, the spectroscopic properties and energy transfer process inYb3+/Ho3+co-doped oxyfluoride germanate glasses under980nm LD excitation areinvestigated. It is found that the emission intensities of upconversion,1.2μm,2.0μm and2.9μm fluorescence increase gradually with increasing concentration of Yb3+. Additionally,energy transfer coefficients between the rare earth ions are calculated.In the fifth chapter, the Ho3+:2.0μm fluorescence sensitized by Cr3+is investigated inthe oxyfluoride germanate glasses. Traditionally Cr3+-doped laser hosts are ideal materialspumped by xenon lamp, however the intense sensitization of Cr3+to Ho3+ensures that theefficient2.0μm emission is achieved by two puming channels: xenon lamp and thecommercial808nm LD. The spectroscopic properties of Cr3+singly doped and Cr3+/Ho3+co-doped oxyfluoride germanate glasses are investigated in detail, and the underlying Cr3+�'Ho3+energy transfer mechanism is rationally demonstrated according to the luminescencespectra.