Supercontinuum generation in untapered and tapered photonic crystal fibers with two zero dispersion wavelengths

Supercontinuum generation in photonic crystal fibers with two zero dispersion wavelengths (ZDWs) is investigated numerically. The role of the second ZDW is examined for 5 fiber designs where the higher ZDW differs while the lower ZDW is almost the same for all fibers. We find that tapering can arrest pump depletion, thereby improving the flatness and bandwidth of the supercontinuum. Pumping with low-power picosecond pulses is also investigated; we find that the low peak power leads to a broad four-wave mixing gain bandwidth, resulting in a supercontinuum that is extremely flat over almost 500 nm.