Optimal Confinement Loss Reduction in Photonic Crystal Fiber with Flattened Dispersion

In this paper, a modified designing method about PCFs with large modal area, low confinement loss and flattened dispersion in a wide wavelength range is proposed. All air holes are arranged in the section according to triangular regulation and with identical spacing. The thirteen air holes which arranged in the snowflake shape in the middle of the section are replaced with high index inclusions that are smaller than the other air holes of the outer cladding which form the core region. So, a hybrid photonic crystal fiber in which a guided mode is confined simultaneously by modified total internal reflection from an array of air holes and anti-resonant reflection from the high-index inclusions is presented. We consider simulating PCF using the FDTD technique by imposing PML for boundary condition treatment in the longitudinal dimension, thereby reducing the problem to two dimensions. Desired dispersion character and low confinement loss can be realized in our designed PCFs with special section structure by optimizing the match of the spacing and air hole size in core and cladding regions and controlling the core-cladding refractive index difference.