Ultrafast four-wave mixing in single-pumped fibre optical parametric amplifiers

Abstract

In this paper we theoretically study ultrafast four-wave mixing (FWM) in fibre optical parametric amplifiers. The nonlinear coupled-amplitude equations are applied to discuss the contributions of self-phase modulation, cross-phase modulation, FWM, temporal walk-off, group-velocity dispersion and third-order dispersion in a degenerate FWM process. In the case of nondispersive FWM, the pulse duration remains nearly unchanged while the shape is distorted and the spectrum exhibits asymmetric broadening in the region where the pump, signal and idler pulses are temporally overlapped. In the case of dispersive FWM, the combined effect of dispersion and nonlinearity leads to both temporal and spectral changes in all the propagation length.