Numerical Analysis of the Nonlinear polarization rotation mode-locked pulses in Fiber

In the nonlinear polarization rotation (NPR) mode locking fiber laser, the electric fields of different intensity of pluses will have different nonlinear phase shifts because of self phase modulation (SPM) and cross-phase modulation (XPM) effects. In this paper we analysis the SPM and XPM effect on the characteristics of pulses in fiber which were influenced when we adjustment the wave plates in the NPR fiber lasers. At the same time, we discussed the pulses waveform´s influence caused by the strength of the SPM and XPM in fibers.