Analysis of birefringent and dispersive properties of photonic crystal fibers.

Two types of high birefringence photonic crystal fiber (PCF) which import four or six big circular air holes near the elliptical-hole are proposed. Their birefringent and dispersive properties are analyzed by full-vector finite-element method (FEM). Numerical analysis demonstrates that importing the big circular hole near the center of elliptical-hole PCFs can achieve a high birefringence. When the ratio (d/Λ) of diameter to hole spacing is larger than 0.8, the proposed two types of PCF have a larger birefringence than that of sole elliptical air hole ones. When the ratio d/Λ is equal to 0.95, the birefringences of these two types PCF can be as high as 4.27×10(-3) and 5.09×10(-3) at the wavelength of 1.55 μm, respectively. Besides, PCF with the four big circular air holes has a large negative dispersion at the long wavelength in x-polarized mode, which indicates a potential in single-polarized mode dispersion compensation.