Preparation Of Ge-based Sulfide Glass Fiber And Its Supercontinuum Properties Research

Supercontinuum spectrum light source refers to the phenomenon that high-power narrow-band laser pulses are coupled into a nonlinear medium to broaden the spectrum,which is the result of the combination of dispersion and nonlinear effects.SC light sourcehas broad application prospects in fluorescence imaging,optical coherence tomography,biological detection,food quality control and pollution detectionetc...Chalcogenide glassesare ideal nonlinear fiber optic medium for broadband SC generationdue to theirextremely wide infrared transmission window(from visible light to 20 ?m),high refractive index,and ultra-high nonlinear coefficient depending on the compositions of the glasses.However,The most efficient SC generation can be obtained in afiber pumped by a wavelength close to the dispersion wavelength(ZDW)of the fiber,the conventional chalcogenide fibers have large material ZDWs(more than 5 ?m),at which thecommercial laser sources are not available and there are rare reports SC generation in near-infrared(even to visible-light)range based on chalcogenideglass fibers.The optimization of the glass composition is expected to realize the blue shift of the zero dispersion point of the chalcogenide glass fiber,which is a direct driving significance for the all-fiber-sulfur mid-infrared supercontinuum source that is pumped by the fiber laser in the future.In this paper,based on a numerous of literature researches,Chalcogenide step-index fibers based on Ge-As-S glasses were fabricated by extrusion method and the loss,mechanical strength and SC broadening properties from this fiber were studied in detail at the laboratory.In the theory,the optical properties of Ge-Ga-S-CsI step-index fibers simulation with different core diameters were used by Comsol Multiphysics software,and the features SC spectrum broadening of Ge-Ga-S-CsI fiber are simulated based on Matlab software.The structure of this paper is as follows:This paper firstly introduced the development process of supercontinuum source and related application fields.The research progress and current status of mid-infrared supercontinuum output of sulfur-based fiber in recent years are reviewed.Supercontinuum was first discovered in bulk glass.After in-depth exploration,the researchers gradually obtained super-wide supercontinuum output in sulfur-based fibers,and continuously explored supercontinuum output media of different structures and materials,which makes the readers with the deep understanding of supercontinuum,and and proposes the research content and significance of this paper.Next,this paper mainly introduces the physical mechanism of supercontinuum broadening.Firstly,the generalized nonlinear Schr?dinger equation is derived from Maxwell's equation,and its solution method is introduced in detail.Finally,the influence of chromatic dispersion and some nonlinear effects on supercontinuum generation is analyzed,which gives readers a better understanding of the mechanism of supercontinuum generationStarting from the selection of fiber matrix glass,the experimental procedure of glass preparation,preparation and purification methods and glass performance test are introduced in the experimental part.The performance test results and analysis of two kinds of glass were introduced at first,and exploring the preparation process of optical fiber preforms.Subsequently,the Ge-As-S step-type optical fiber preform was prepared by extrusion method and drawn into an optical fiber.In addition,the loss and mechanical properties of the fiber were analyzed in detail.Finally,the Ge-Ga-S-CsI fiber drawing process was explored.In addition,the output characteristics of Ge-As-S step-type fiber supercontinuum experiments are studied.The mid-infrared supercontinuum output characteristics under different pump wavelengths and different power conditions are analyzed.The optical properties of Ge-Ga-S-CsI stepped fiber with different core diameters andthe infrared supercontinuum output characteristicswere simulated by Comsol Multiphysics and Matlab software,respectively.Finally,we make a summary of this paper and the shortcomings in the work.