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

The strong waveguide dispersion in photonic crystal fibres (PCFs) provides unique opportunities for nonlinear optics with a zero-dispersion wavelength λ 0 far below the limit of ∼1.3 μm set by the material dispersion of silica. By tuning the air hole diameter d , the pitch Λ, and the number of rings of air holes N , the strong waveguide dispersion can in principle be used to extend λ 0 well into the visible, albeit to some extent at the cost of multi-mode operation. We study in detail the interplay of the zero-dispersion wavelength, the cutoff wavelength λ c , and the leakage loss in the parameter space spanned by d , Λ, and N . As a particular result, we identify values of d (∼ 500 nm) and Λ (∼700 nm) which facilitate the shortest possible zero-dispersion wavelength (∼700 nm), while the fibre is still in single-mode for longer wavelengths.