Numerical simulations of high power near-infrared supercontinuum generation from a nonlinear fiber amplifier

Abstract

Photonic crystal fiber has been widely used in visible and near-infrared supercontinuum generation due to its flexible dispersion control and high nonlinearity. However, the maximum average output power of supercontinuum from a photonic crystal fiber has not exceed one hundred watt owing to the small core diameter of the photonic crystal fiber and the low coupling efficiency between the pump and the photonic crystal fiber. Recently, supercontinuum generation directly from a nonlinear fiber amplifier attracts lots of attention as a result of its simple structure and low splicing loss and many excellent results have been achieved either in low and high average power, which is proved to be a promising method to realize kilowatt level high power near-infrared supercontinuum. However, the numerical study on high power near-infrared supercontinuum generation from a nonlinear fiber amplifier has been rarely reported, so there is great necessity to carry out some theoretical study on it. In this paper the complex Ginzburg-Landau equation is used to describe the formation and propagation of high power near-infrared supercontinuum generation in a nonlinear fiber amplifier. The chromatic dispersion of the ytterbium-doped fiber is measured by a Mach-Zehnder interferometer. The roles of the small signal gain, input pulse width and initial chirp of the input pulse played on the continuum formation are analyzed in detail. The results are in good agreement with the experiments which can provide some theoretical guidance on future optimization of the flatness and width of the supercontinuum generation from a nonlinear fiber amplifier.