Glass Preparation And Optical Properties Investigation Of Sn-doped Chalcogenide Glasses

In the recent years,with the development of the research carried on the optical communication,all-optical information and optical computer,the application of all-optical instruments like optical switch?optical wave converter and optical filter gets more and more attention in the society.However,in order to achieve this goal,the preparation of materials with excellent nonlinear properties has become very essential.Among the investigation of nonlinear optical properties,the third-order nonlinearities of materials have been widely studied due to its essential role in deciding the application of all-optical instruments.In the meanwhile,chalcogenide glasses have been confirmed as the most potential materials for all-optical switches by taking advantage of their wide infrared transmission range?high transmittance in the rage of 3 to 5 ?m and 8 to 14 ?m??high refractive index?good thermo-chemical stability and large third-order optical nonlinearity,especially compared with the traditional oxide glasses,the nonlinear refractive index of chalcogenide glasses can be 100 to 1000 higher than that of oxide glasses along with fast respond time shorten than 200 fs.The main purpose of this study is to obtain different component chalcogenide glasses by using a series of methods,and then have a systematic analysis on the glass structure?optical properties and third-order nonlinearities and the relationship between each other,and finally obtain the most proper materials for the application in optical communication.The detailed discussions are shown followed:?1?The research on spectral characteristic and threshold behavior of Ge-Sb-S chalcogenide glasses.Two series of Ge-Sb-S ternary chalcogenide glasses are synthesized by melt-quenching method.The phycochemical properties and spectral characteristic of glasses under different content of Ge and Sb elements are obtained by a series of measurements,and the systematic analysis on the change of optical properties can be studied in terms of microstructure of glasses combined with the Raman spectra.Using the theory of mean coordination number?Z?,we can describe the variation trend of network structure directly and find that once the value of Z is over 2.6,new obvious peaks will occur in the Raman spectra indicating the generation of threshold behavior in the network structure of glasses and the obvious variation of composition of glasses.The appearance of new forms of functional groups in the network have changed the total bond energy of glasses,and then affected the energy band structure of glasses representing the corresponding threshold behavior of the value of optical band gap?Eopg?.?2?Improved nonlinear optical properties of chalcogenide glasses in Ge-Sn-Se ternary system by thermal treatment.In this work,a series of chalcogenide glass ceramics were prepared by thermal treating a precursor glass in molar composition of Ge₂₀Sn₅Se₇₅ with different duration.XRD measurements showed the precipitation of nano-crystals belonging to GeSe₂ and SnSe₂ phases in the heat-treated glasses,which was confirmed by Raman spectra as well.The crystallization in glass matrix caused the variation of optical properties?i.e.Optical band gap,Urbach energy?due to localized field effect of the nano-crystals,while the infrared transmittance was kept unchanged.Third-order optical nonlinear properties of the precursor glass and glass ceramic samples were investigated by femtosecond Z-scan technique at telecom wavelength of 1550 nm.The maximum nonlinear refraction???of the Ge-Sn-Se glass ceramics reached 5.319×10^-16 m²/W,which is almost one order higher than that of the precursor glass,demonstrating the significant influence of nano-crystals on optical nonlinear property of the chalcogenide glasses.?3?Glass formation and mid-infrared optical nonlinearities of chalcogenide glasses in germanium-tin-sulfur ternary system.Glass forming region of chalcogenide glasses in germanium-tin-sulfur?Ge-Sn-S?ternary system is depicted.Three series of Ge-Sn-S glasses in different compositions are selected and synthesized,in order to investigate the dependence of structural,optical and third-order nonlinear properties on chemical composition.Spectroscopy analyses manifest that Ge and Sn have the similar structural behavior in the glass network,while the introduction of Sn deceases the optical bandgap energy and improves the infrared transmittance of the glasses.Third-order nonlinear properties of the glasses are investigated by Z-scan technique at mid-infrared wavelength of 3.3 ?m.The experimental results demonstrate that the nonlinear absorption at the mid-infrared wavelength is absent due to the large optical bandgap energy of the glasses,while the nonlinear refractive behavior is evident and can be improved by reducing number of [GeS₄] tetrahedrons in the glass network.