VALIDITY OF SEPARATING GROUP-VELOCITY DISPERSION OF PHOTONIC-CRYSTAL FIBERS INTO MATERIAL AND WAVEGUIDE COMPONENTS

摘要

Based on the effective index model of an endlessly single-mode photonic-crystal fiber, the analysis of group-velocity dispersion (GVD) can be separated into material and waveguide components. In this paper, the validity of this approach is examined. The separation is shown to be valid only at small air-hole diameters, where the variation of the effective index of the cladding closely follows that of the core. We illustrate the fact that more accurate results of the GVD can be obtained by using a numerical method which avoids separation into the above components, and taking into account the wavelength-dependent behavior of the refractive index of silica.