Waveguide characteristics of single-mode microstructural fibres with a complicated refractive index distribution profile

The method of equivalent step profile of the refractive index is used to calculate the main waveguide characteristics of single-mode microstructural fibres (MFs). A new structure is proposed for such fibres with a W-shaped profile of the refractive index distribution. The dispersion characteristics of such fibres were calculated by solving the scalar wave equation. It is shown that the chromatic dispersion zero may shift to the blue (λ₀ ≈ 0.8 μm) in such structures while the single-mode propagation regime is preserved. A number of MF structures with a complicated distribution of the refractive index profile are proposed and the possibility of assembling such structures in circular quartz tubes is discussed.