Research And Design Of Photonic Crystal Fiber With Large Effective Area

In order to search fiber with large effective area, this paper shows searching in photonic crystal fibers first.And then conduct research and analysis and design in the new LPF (Large-pitch photonic fibers) are metioned. In dense wavelength division multiplexing transmission system, as one of the factors of the limiting the transmission capacity and transmission distance of fiber, nonlinear effects become the object of study. The increase of the effective area of the optical fiber enables that the optical fiber nonlinear effects can be significantly reduced. So that the relay distance prolongs and the number of channels increases which improve the level of the optical power of the optical fiber transmission. Using of the LPF brung the following advantages:(1) a highly scalablity where smaller structure sizes are required to change for the increase of effective area;(2) a fairly large range of hole changing while keeping single-mode transmission.First, paper began to study from regular photonic crystal fibers.Photonic crystal fibers became one of the focus because of its many features and excellent prospects.The paper elaborate some basic theory and characteristics of the photonic crystal fibers. And the reasons of all characteristcs were explained.Then, in oder to get accurate analysis and predict characteristic of transmission of the photonic crystal fibers,people developed a lot of theoretical analysis methods,such as finite element method,the effective refractive index of the model approach,scattering matrix method,time domain-ray transmission method,finite difference time domain method,plane wave method,etc.These theoretical models plays important part in research in photonic crystal fibers.The paper did further study in the advantages and disadvantages of each model,then chose finite element methos as the primary method to research.In the end of the paper, through the combination of COMSOL Multiphysics finite element method,the simulation of photonic crystal fiber and simulation of several different structures (hexagon and square)of the LPF and analyzing of its parameters achieved. After analysising of crystal fiber and research of the finite element method the author simulates and practices much in changing parameters in order to konw what kind of changes inparameters will make certain change in the effective area.The effective area of LPF can achieve as high as7246.38μm2when the wavelength equals to1550nm and the same time the perfect isolation layer has a inside diameter of85μm. The paper verified the excellent simulation capabilities of the COMSOL Multiphysics, and afford theoretical data for the further study of the LPF at the same time.