The impact of the cross-phase modulation (XPM) on the performance of NOLM in the single-wavelength channel and WDM channel is studied by using the split-step Fourier method (SSFM) that can solve the coupled nonlinear Schroedinger equation (CNLSE). The numerical simulation results show that the switching performance of NOLM is distorted by the XPM induced nonreciprocity when the splitting ratio of NOLM coupler 0.5 f ≠ and the distortion effect would be more serious with the increase of the working speed. The power transmission function of NOLM decreases in the range of f ∈ (0,0.5) and increases in the range of f ∈ (0.5,1). Furthermore, the impact of XPM induced by the crosstalk of wavelengths is far more than that of XPM induced by the overlap of counter-propagating optical components in the WDM channel. Pedestals are leaked from the main lobe appear and the pedestals of the middle wavelengths are larger than those of the edge wavelengths.
The impact of the first-order and second-order PMD on the performances of optical switching with NOLM is studied by the split-step Fourier method (SSFM) based on the coupled nonlinear Schrodinger equation (CNLSE), including optical eye graphs, power transmission function of the NRZ code and the Q-factor penalty of different code patterns at different working speeds. The simulation results show that the switching performances are deteriorated badly by PMD, and using the right code pattern can reduce the impact of PMD partially. Furthermore, the compensation method of PMD by the polarization-maintaining fiber (PMF) inside the fiber loop of NOLM is put forward. It influences the original switching performances to the least extent when the PMF is located in the middle of the fiber loop.