Structure Design And Transmission Characteristics Of SiO₂ Photonic Crystal Fiber

Optical fiber,as one of the important tools in the information age,has brought rapid development and progress to the communication field.In recent years,the communication mode of our country gradually develops to the all-optical fiber mode.Optical fiber communication technology has the advantages of large communication capacity,strong anti-interference ability,high security and low transmission loss of waveguide.It is one of the most important technological achievements in the 20th century.Corning successfully developed quartz fiber with a transmission loss of 20 dB/km in 1970,and fiber technology has been rapidly developed since then.Photonic Crystal Fibers(PCFs),as the most promising field in Photonic crystals,have attracted extensive attention of scholars in various fields in recent years.Fiber materials are constantly changing,but its principle and structure have not changed greatly.The difference is that photonic crystal fiber,as an optical channel compared with ordinary fiber,provides a new method to control and guide light.PCF has excellent optical properties such as infinite single mode,high birefringence,high nonlinearity,low limiting loss and high birefringence,so it has objective application prospect in many fields.PCF is flexible in structure design,so this paper will try to design a PCF with high quality optical performance by starting from the physical basis of how to design the cross section of photonic crystal fiber and combining with various geometric factors that can affect the optical performance of the fiber,such as the shape,size and position of pores.The optical properties of the optical fiber under the corresponding structure were simulated by using COMSOL Multiphysics5.5 multi-field coupling software and full-vector finite element analysis(FEM).This paper presents the detailed research steps of numerical simulation of photonic crystal fibers using COMSOL Multiphysics,explores the influence of duty cycle and air hole spacing changes on optical properties,and proposes two kinds of structure PCF based on the octagonal arrangement of circular air holes:Based on the original model,the circular air hole was changed into an ellipse,and a series of optical properties of PCF were explored by changing the layer number of air holes.Through numerical simulation,found in this paper,the design of PCF with smaller effective fiber core area,smaller limit losses,better able to limit optical signals in the fiber core area,reduce the distortion in the process of signal transmission,at the same time the PCF has high nonlinear coefficient,maximum of 110W-1km-1 for high provides a good model of nonlinear optical fiber,Moreover,there is zero dispersion wavelength near 1.55 ?m,which can reduce the optical pulse distortion.In comparison,PCF with one ring of air hole has good polarization keeping performance,and has a large birefraction value in the whole range of execution wavelength,up to 0.021,which supports the high-precision measurement of physical quantity in the polarization keeping equipment.