improvement of optical properties in hexagonal index-guiding photonic crystal fiber for optical communications

waveguides with low confinement loss, low chromatic dispersion, and low nonlinear effects are used in optical communication systems. optical fibers can also be employed in such systems. besides optical fibers, photonic crystal fibers are also highly suitable transmission media for optical communication systems. in this paper, we introduce two new designs of index-guiding photonic crystal fiber (igpcf) with characteristics appropriate for optical communications. in the first proposed design with a hexagonal structure having a defect at the center, the chromatic dispersion at the wavelength of 1550 nm is less than 1 ps/(nm.km). in the second design with a hexagonal structure having air holes with unequal diameters, nearly zero dispersion at the wavelength range of 1370 to 1380 nm is achieved. at the same time, for the latter design, at the wavelength of 1550 nm, the chromatic dispersion slope is1 ps/(km.nm), the confinement loss is less than 10-9 db/km, and the nonlinear coefficient reaches 3.690 w-1.km-1.