Effect of frequency chirp on supercontinuum generation in photonic crystal fibers with two zero-dispersion wavelengths

Abstract

The effect of initial frequency chirp is theoretically investigated in photonic crystal fibers with two zero-dispersion wavelengths. Based on numerical simulations, it is shown that there exits an optimal propagation distance whether input pulse is chirped or not, where spectrums have maximal bandwidth. Furthermore, contrary to the complicated spectrum structure generated by negative-chirped pulse, positive linear chirp enhances supercontinuum generation and spectrum is much more regular. The efficiency of four-wave mixing is also improved because of initial positive chirps, and for enough large chirp values the incident pulse energy in the anomalous dispersion region is almost thoroughly transferred to the visible and near-infrared regions outside two zero-dispersion wavelengths.