Modal analysis of holey fibres with convex and non-convex polygon-shaped holes

摘要

The plane wave and localized function expansion methods are established for bandgap and modal calculations of holey fibres. The calculations rely on evaluating the Fourier transform coefficients of the dielectric constant pro. le. In this paper we derive a generalized formula for determining these coefficients for holey fibres with holes of arbitrary polygonal shape. The accuracy of the Fourier representation is studied for different hole shapes rotated at various angles to the lattice. We combine the approach with the localized function method to study the modal properties of some holey fibres, reporting new numerical results on the influence of the hole shape on the modal and group velocity dispersion of microstructured fibres with rhombic holes aligned along radial lines.