Improving the birefringence using a graded core photonic crystal fiber

In this paper we report the control of birefringence in octagonal-lattice photonic crystal fiber by doped gradually the central part of the core. Based on our results, the birefringence is found to be largely on the variation of the materials, number of elliptical air holes ring and diameter of the graded core region. The maximal model birefringence of our proposed PCF at the excitation wavelength of lambda = 1550 nm can be achieved 7.12 x 10(-3). The Finite Difference Time Domain with Transparent Boundary Condition is used to analyze such PCF.