Preparetion Of Rare-Earth Ions Doped Fluoroaluminate Glass And Investigation On The 3?m Mid-Infrared Emission Properties

Since the birth of the first ruby solid-state lasers,the laser technology has been developed 50 years.Laser technology has now been widely used in all aspects of life,and 3?m solid-state lasers have drawn considerable attention due to their wide and important applications,including medical treatment,environmental monitoring,military defense,and so on.The rare earth activated ions used in the middle infrared3?m are mainly concentrated in Er³⁺,Dy³⁺and Ho³⁺ions.At present,the laser glass matrix,such as heavy metal oxide,fluoride and sulfur glass,are widely studied due to the low phonon energy and excellent optical properties.In the past,the study of the fluoride glass mainly confined in the fluorozirconate?ZBLAN?system,At present,the glass of ZBLAN system with a variety of rare earth ion doping has been used as the most mature glass substrate for optical devices.However,the fluoroaluminate glass system have been rarely studied due to the characteristics of its crystallization,In order to overcome this problem,many researchers try to add oxide to improve the thermal properties of the glass.In addition,in view of excellent optical properties of the fluoride glass,the chloride possessing the low phonon energy is doped as a modifier in the fluoride glass.Therefore,oxides and chlorides add to fluoride glass as modifiers to explore a new type of fluoride glass system with excellent thermal stability and mid-infrared spectroscopy.And the luminous properties of the glass with rare earth ions doped and sensitization of sensitized ions to the activated ions are investigated,so as to provide suitable rare-earth ions doped laser materials for 3?m ultra-short pulse laser applications.This dissertation includes the following five chapters.In chapter 1,the applications and research progress of fiber lasers operating at 3?m region have been reviewed.Active ions and mechanisms to generate fluorescence or laser at 3?m region were introduced.Finally,the purpose and research content of the dissertation were represented.In chapter 2,the experimental methods were introduced,including the preparation procedures of fluoride glasses,measurements of the physical and spectroscopic properties,and theory analysis.In the chapter 3,the mid-infrared luminescence characteristics of the AYF system and the fluoride modified by TeO₂ system with high concentration of Er³⁺were studied.Thermal,structural and spectral properties of AYFCl glass are analyzed and the mid-infrared spectra of Er³⁺in AYF,AYFO and AYFCl glasses were compared.The doping concentration of Er³⁺ions in AYF glass is 13mol%.With the increase of Er³⁺ion concentration,the fluorescence intensity and emission cross section at 2.7?m increase,and the fluorescence lifetime decreases.The?T of AYFO glass with 10mol%TeO₂ was increased to 98°C compared to AYF glass,showing good thermal stability.However,the hydroxyl absorptioncoefficient(0.44cm^-1)is large,and 2.7?m fluorescence quenched when Er³⁺ion concentration was 11mol%.In addition,AYFO glass exhibits good broadband characteristics in 1.5?m near infrared field.Both the AYFO glass modified by O^2-and the AYFCl glass modified by Cl^-have better thermal properties than AYF,where the thermal stability of the AYFCl glass is the best.According to the fluorescence spectra and decay curves of Er³⁺ions in AYF,AYFO and AYFCl glasses,it can be found that the mid-infrared optical properties and fluorescence lifetime of AYFO glass are lower than those of AYF glass,and the AYFCl samples which possessing lower phonon density and hydroxyl content,have a good thermal,optical properties and fluorescence lifetime.Thus,the chloride is more suitable as a modifier for the pure fluoride AYF glass matrix.In chapter 5,the 2.9?m optical properties of Dy³⁺singly doped and Yb³⁺/Dy³⁺co-doped AYFO glasses under 808 nm and 980 nm LD and analyzed the sensitized effect of Yb³⁺on Dy³⁺have been researched.The 2.9?m emission intensity of Dy³⁺has been enhanced via the Yb³⁺:²F_5/2?Dy³⁺:⁶H_5/2/2 energy transfer process under 980nm LD.Meanwhile,the emission cross section of Dy³⁺around 2.9?m also has been increased from 0.416×10^-20cm² to 0.522×10^-20cm².The energy transfer efficiency of Yb³⁺?Dy³⁺reaches as high as 80%.All results indicate that the efficient sensitization on Yb³⁺to Dy³⁺can be realized under 980 nm LD.Another point in this chapter is the sensitized effect of Nd³⁺on Dy³⁺in AYF glasses under 808 nm LD.The effect derived from the Nd³⁺:⁵F_5/2(²H_9/2)?Dy³⁺:⁶F_5/2/2 and Nd³⁺:⁴F_5/2?Dy³⁺:⁶F_7/2/2 process transfer energy to near Dy³⁺level.1.5 times enhancement of 2.9?m emission was achieved successfully in the effect of Nd³⁺,the lifetimes of ⁶H_13/23/2 level and emission cross section have been increased to 270?s and 0.522×10^-21cm²,respectively.All results suggest that the efficient energy transfer between Nd³⁺and Dy³⁺can be achieved successfully.Finally,it was the conclusion of this dissertation,which generalized the innovative results of this dissertation and pointed out the drawbacks that needed to be improved.