Research On Composition, Structure And Optical Properties Of Ge(s_xse_1-x)₂ Chalcogenide Glasses

Chalcogenide glasses have wide application prospect in the fields of infrared detection,reversible optical recording medi,all-optical switching,inorganic photoresists and so forth due to their wide infrared transmission windows,high linear and nonlinear refractive indices and excellent photosensitivity. Considering the intimate relationship between the properties and structure, micro-structural investigation of chalcogenide glasses has important academic and practical meanings. Based on continuously tunable characteristic of composition and properties for Ge(SxSe1_x)2 glasses, a systemic study on the influence law of S or Se replacement to their microstructure and optical quality was conducted in the present work. Moreover, Ge(S0.8Se0.2)2 chalcogenide glasses were chosen to study the micro-crystallization law.Aiming at the previous analysis of Raman spectra evolvement only for Ge(SxSe1-x)2 (0=x=0.25) glasses, in this study, Ge(SxSe1-x)2 (0=x=1) glasses were prepared by conventional melt-quenching method using high purity Ge, S and Se (all of 5 N) as raw materials through preparation technical optimization. Microstructure evolution law of Ge(SxSe1-x)2 glasses was described by Raman scattering technology and positron annihilation technology. Raman scattering results show that microstructure unit model of Ge(SxSe1_x)2 glasses does not change along with S or Se replacement, tetrahedral unit configuration is preserved, namely [GeSnSe4-n] (n=0,1,2,3,4); but the distributing of [GeSnSe4-n] (n=0,1,2,3,4) tetrahedra in glass changes. Researches on positron annihilation lifetime detect that while S or Se replacement up to a certain value, open volume of the glass is smallest. Refractive index characterization shows that the change of refractive index presents a simple linear evolution which can be reasonably explained base on microstructure unit distributing evolvement law of Ge(SxSe1-x)2 glasses.Give attention to visible transmission and high nonlinear capability, Ge(S0.8Se0.2)2 glasses were chosen to study the second-order optical nonlinearity of obtained glass ceramics. An efficient heat treatment to permanent second-order optical nonlinearity was achieved in Vis-IR transparent chalcogenide glass ceramics. In order to keep the high transmisssion spectra, the time of 470℃(Tg=468℃) heating treating of Ge(S0.8Se0.2)2 glasses should be under 24 hours according to the Vis-NIR spectra. Using Maker fringe method describe SHG performance of prepared Ge(S0.8Se0.2)2 glass ciramics, calculated results show that the highest second harmonic coefficientx(2) of Ge(S0.8Se0.2)2 glass ciramics is up to 3.54pm/V.