Research On Fabrication And Performance Of Chalcogenide Glasses Hollow-core Photonic Crystal Fiber

Hollow-core photonic crystal fiber completely different from the traditional optical fiber on the fiber structure,guiding mechanism and transmission characteristics.The fiber can suppress highly the optical absorption and nonlinearities of their constituent materials,which makes them viable candidates for transmitting high-peak power pulses.The advantages of chalcogenide glasses as low intrinsic loss,wide infrared transmission,chemical stability and mechanical performance makes the best choice for developing low loss and long wave infrared glass materials.In this thesis,chalcogenide glasses are selected to prepare the hollow core photonic fiber with one-dimensional period structure,also called hollow core Bragg fiber.Firstly,a sire of chalcogenide glasses were purified and fabricated by method of distillation method and melt-quenching method,then optical and thermal properties are deeply studied,finally,high purity glasses with little obvious absorption peaks were prepared.Secondly,we design and improve the extrusion mould,successfully achieved hollow core Bragg fiber perform with good cross-section structure.With the help of Rsoft software,we simulated the fiber bandgap,optimized the lattice period and their designing of basic structure,then,a bragg fiber with uniform periodic structure was obtained by drawing method.The first chapter of the thesis is a brief introduction of the chalcogenide glass and development status of photonic crystal fiber,the structure characteristics and advantages of Bragg fiber,then introduced and compared three kinds of technological process of preparation of photonic crystal fiber in detail.In the second chapter,some theoretical basis of chalcogenide glass and fiber were introduced.The theoretical basis of chalcogenide glass includes the definition and structure of glass,thermal properties including glass transition temperature and thermal expansion coefficient,band gap,optical transmission spectral,absorption peaks and chemical reacting principles in glass purification and so on.The basic theory of optical fiber included light transmission principle of hollow core bragg fiber,the influence of structure parameters on the performance,loss and their originals and so on.In the third chapter,the As-S,Ge-P-Te,Ge-As-Se-Te glass properties such as physical,thermal stability and infrared transmittance were discussed,summarized the improvement after the process of purification and influence of glass properties with the content changing of Se,chosen glasses with best matching as the basic materials.In the fourth chapter,the structural model of the hollow core Bragg fiber were designed based on the parameters of refractive index of chosen glasses As2S3,Ge15As25 Se15Te45.After all,it need to determine the lattice period,the optical fiber cladding material thickness and radius parameters when it can produced bandgap at the wavelength of 10.6?m.In the fifth chapter showed the main fabrication processes of infrared hollow core Bragg fiber,included the extrusion of the fiber performer and the fiber drawing process,by the way of improve the extrusion mode and change the temperature parameter to obtain the performer with better,by the way of control the temperature parameter,the speed of the drawing and feeding,the intensity of ventilation pressure to get the fiber with nice structure,then test the performance of the optical fiber at last.At the last of the paper,summarized the work,presented the research achievements and encountered difficulties in the process of research,analysed the reason why the difference between actual preparation of the fiber and the theoretical value.After all,we provided a experimental basis for preparation of low loss hollow-core optical crystal optical fiber with perfect structure in the next step.