Peculiarities of the coherence time of a spectral supercontinuum generated in microstructured fibers with two zeros in the group-velocity dispersion

Abstract

We used a numerical simulation to calculate the coherence time of the spectral supercontinuum generated in a microstructured fiber in which the group velocity dispersion as a function of wavelength and pump pulse width has two zeros. We determined the contribution to the total coherence time from each of the separate substructures in the resulting spectral supercontinuum for various models of the initial pulse parameters. We show that, near the zeros in the group-velocity dispersion, the spectral supercontinuum coherence time is observed to be a rapidly increasing function of the central wavelength of the initial pulse. This is because the primary contribution to the coherence time near the zeros in the group-velocity dispersion in such cases comes from regular structures formed during generation of the supercontinuum. At intermediate wavelengths between the zeros in the group dispersion, the contribution to the interference signal from the regular structures shifts from one substructure to another and depends on the central wavelength of the emission.