Gradient Analysis Of Photonic Crystal Fiber Core Approximation

In this paper, the effective refractive index in the cladding of a photonic crystal optical fiber is analyzed according to the model of effective refractive index. The photonic optical fiber is treated as a fiber whose refractive index of core distributed as square law in radius. The formulae for optical field in the total-refractive-kind fibers are deduced in scalar method. On this base, the influences of constructive parameters of fiber and frequency to the field, and the so-called "endless single mode property", are discussed with the help of the mathematic tool, Matlab. Several distribute curves for lower order modes are drawn.In the First chapter, the history of theory and applying of optical fiber, and the classification of photonic optical fiber, are reviewed simply. Several analyzing methods for different modes of optical fibers are outlined, too. In Second chapter, the rough situation about researching work on photonic crystal optical fiber is introduced. On this base, the research direction of this paper is brought forward, and its feasibility is discussed. The theoretical analysis for total-reflection-kind photonic crystal optical fiber is made in Third chapter. According to the characteristic equation, the curves of effective refraction index of cladding, and the refraction index of core, varying with wave length and effective radius of core are obtained. In fourth chapter, the property of modes and radial distribution of field are discussed. The Fifth chapter is a conclusion.