Nonlinear photonic crystal fibres: pushing the zero-dispersion toward the visible

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The strong waveguide dispersion in photonic crystal fibres provides unique opportunities for nonlinear optics with a zero-dispersion wavelength λ₀ far below the limit of 1.3 micron set by the material dispersion of silica. By tuning the air-hole diameter d, the pitch Lambda, and the number of rings of air holes N, the strong waveguide dispersion can in principle be used to extend lambda₀ well into the visible, albeit to some extend at the cost of multimode operation. We study in detail the interplay of the zero-dispersion wavelength, the cut-off wavelength lambdac, and the leakage loss in the parameter space spanned by d, Lambda, and N. As a particular result we identify values of d (500 nm) and Lambda (700 nm) which facilitate the shortest possible zero-dispersion wavelength (700 nm) while the fibre is still single-mode for longer wavelengths.