Investigation of the Index Profile of Photonic Crystal Fibers on Dispersion Characteristics

Using a vector finite-element method, this paper theoretically explores the index-profile induced dispersion characteristics in a photonic crystal fiber of hexagonal symmetry. The cross section pattern of two dimensional PCF comprises five layers of elliptical hole with one hole missing in the center. The direction and size of the third layer are different from the other layers. We keep the area of each hole abiding and change the length ratio, which leads to different index-profiles. Considering fundamental mode, the results show dispersion characteristics are strongly depended on the length ratio. The dispersion changes from -20 ps/nm · km to 20 ps/nm · km within the range of wavelength 1.25μm~1.65μm. The zero dispersion wavelength blue shifts when the length ratio decreases with the same air filling fraction. At 1.55μm wavelength, we achieved confinement loss up to 10-5dB/m and near zero dispersion by designing length ratio to 1.44.