| The chalcogenide glass fiber has excellent mid-infrared transmission characteristics,and has acted an important part in space detection,infrared imaging,laser transmission,optoelectronic devices,remote sensing,and national defense security.In the material preparation,we adopted As-Se chalcogenide glasses,as that possess much good thermal stability and excellent near-mid-infrared performance as the fiber matrix material.There are two key points in how to prepare low-loss chalcogenide glass fibers.One is to reduce the impurity content in the glass,and the other is to optimize the preparation process of the chalcogenide glass fiber.That are the key factors for preparing low-loss chalcogenide fibers.In this thesis,we first use the heating method for dynamic vacuuming,and then adopt an active distillation purification method for raw material purification.Two sets of As-Se glass were prepared,and small core singlemode and large core multimode fiber were prepared by traditional isolation extrusion method and peel-off isolation extrusion method,and the lower fiber loss was obtained.Finally,light field energy analysis and supercontinuum testing were performed.In the first chapter,we briefly outline the chalcogenide glass and the chalcogenide glass fiber.The optical properties and application fields of the chalcogenide glass are introduced.By comparing the currently practical sulfur-based fiber,we have chosen the cost-effective As-Se glass research.The preparation process of chalcogenide glass fiber was introduced respectively.Finally,the improved isolation extrusion method has its own unique advantages.In the second chapter,we introduce the theory of chalcogenide glass and the basic characteristics of glass,such as infrared transmission spectrum,thermal expansion,impurities and defects,and introduces the necessity of glass preparation and purification.The theoretical basis of optical fiber includes fiber structure and transmission,fiber loss and fiber dispersion.In the third chapter,we first introduce the purification process and preparation method of chalcogenide glass.The As40Se58Te2/As40Se60 and As38Se62/As39Se61 bulk glass are obtained respectively,and then the glass is further machined.Finally,the transmission spectrum and refractive index of the glass are tested.In the fourth chapter,we introduce twice multi-step isolation extrusion method(ISE)to prepared single-mode As-Se chalcogenide glass fiber.The fiber drawing process is described in detail.The structure and end surface of the fiber are analyzed respectively.The fiber supports single-mode transmission conditions.The test analyzed fiber loss and supercontinuum.In the fifth chapter,we present an innovative peeled-off ISE,which has advantage of decreasing the core/cladding defects compared with the traditional ISE.The fiber preform and cross section were analyzed in detail.The optical field energy distribution of the fiber is obtained by testing,and the fiber has excellent light transportation ability.By comparing the fiber loss of the two extrusion methods,it can be concluded that the peeled-off ISE can solve the problem of scattering of light with increased core-clad defects,and effectively reduce the loss of the fiber.The results of supercontinuum(SC)show that a flatted SC spectrum can be obtained in this large-core fiber with femtosecond optical parametric amplifier(OPA)laser pumping.At the last,some key parameters to the preparation of low-loss As-Se chalcogenide glass fiber are summarized,and some suggestions are given for the succeeding works in the future. |
