| Chalcogenide optical fibers have wide potential application in the field of infrared laserenergy delivery, medical tests, and fiber optical sensing, on the base of its excellent IR opticalproperties. Meanwhile, with development of optical nonlinear, more and more need to have highnonlinear chalcogenide glass fiber in the field of optical fiber communication. The chalcogenideglass fiber possesses some advantages, such as ultra-high nonlinear (the highest in glass fiber),adjustable optical cut-off wavelength, tunable refractive index and stable optical performance andetc. Meanwhile, it is hard to select the chalcogenide glass composition as the most optimizedoptical fiber materials, which were generally decided by the properties of physical, chemical,anti-crystallization and so on. In all, it is need to choose a host glass with high transparency andwide range of infrared transmission. The nonuniform structure and impurities are increasing theoptical scattering loss, so how to reduce the content of the impurities is the key part of low losschalcogenide glass fiber preparation. Now, many kinds of preparation methods can’t achieve thelow loss requirement and the chalcogenide glass fiber is also fragile so it can’t adopt the traditionalorganic liquid coating method for protecting.In view of the problems in chalcogenide glass fibers research, the heavy-metal and metalhalide are introduced into chalcogenide glasses to improve the performance of glasses. TheGe-Ga-Te-Cu and Ge-Ga-Te-ZnI2glass systems have been reported. The present work aims tostudy the formation and properties of Te-based glass system with XRD, SEM and DSC. Infraredoptical transmission spectra are carried out to investigate the properties of glass. The glassGe15Sb20S65and Ge25Sb5Se70are selected for distillation as their better thermal and plasticityproperties. A new coextrusion method is adopt to fabricate the fiber perform, and then, the preformis jacked with the polymer for fiber drawing. After a well polishing process, the optical loss andbend loss are tested.In Chapter one, the chalcogenide glass and chalcogenide glass fibers are summarized, thelatest development and application in different fields of infrared optical fiber are introduced and thetraditional optical fiber preparation methods are also mentioned. Then, the research contents of thisthesis are also summed up.In Chapter Two, the glass theoretical basis is introduced, such as thermal properties, opticalband gap, energy band gap, IR-cut edge theory and purification. The fiber theoretical bases includeoptical structure, fiber attenuation, fiber nonlinear and optical fiber transmission theory. In Chapter Three, the glass prepration methods and the main test methods of chalcogenideglasses are illustrated. At the same time, the preparation process of novel low-loss chalcogenideglass optical fiber and the performance test of the fiber are also introduced.In Chapter Four, effect of Cu on the formation and properties of Ge-Ga-Te chalcogenideglasses is studied. The results show that with the increasing of Cu content, both the density and themolar volume of the glasses decrease. A red-shifting occurs in the short-wavelength absorptioncut-off edge of the glasses, the band gap decreased. A maximum ΔΤ value of103oC is obtained forthe glass composition (GeTe4)68(Ga2Te3)26Cu6.These prepared GeTe4-Ga2Te3-Cu glasses all havewide optical transmission window and the infrared cut-off wavelength is far beyond20μm. Themain absorption bands Ga-O in IR region can be eliminated when500ppm Al is added into glass.In Chapter Five, ZnI2is added into Ge-Ga-Te glass system and the glass-forming region isdetermined. The effect of ZnI2on the formation and properties of Ge-Ga-Te chalcogenide glassesare studied. The results show that with the addition of ZnI2, the values of ΔT increase for thechalcogenide glasses and the values of indirect optical band gaps are observed with ranges from0.596to0.626eV in these glasses. The studied glasses have a wide optical transmission windowfrom1.9to25μm.In Chapter Six, the fabrication and properties of Chalcogenide optical fiber based on a newextrusion method are introduced. Ge15Sb20S65and Ge25Sb5Se70bulk chalcogenide glasses withdifferent size are prepared and their physical, thermal and optical properties are discussed in detail.The structure of cross-section all can be modified freely with an optimized designation of die size.Then, the preform is jacked with a high strength and high temperature polymer. After that, thepreform is drawn into fibers with a specialized fiber drawing tower. The well-controlledcross-section of fiber with uniform and clear structure is verified by an optical microscope after awell polishing process. Fourier transform infrared spectrometer is performed to determine theoptical loss. As shown in the transmitting loss spectra, the lowest optical loss of the fiber is2.61dB/m at wavelength of4.8μm. The optical fiber with the protection of polymer, when the bendangle increase in a certain range, the optical bend losses basically remain unchanged.At the last, all results of this thesis are outlined, and some suggestions are given for thesucceeding works in the future. |
PDF Full Text Request