Small-signal analysis of cross-phase modulation instability in lossy fibres

摘要

Based on the small signal analysis theory and split- step Fourier method, the complex nonlinear Schrodinger equation ( NLSE) with. fibre loss can be solved. This procedure is also adapted to the NLSE with the high order dispersion terms (beta(3), beta(4)). Because the. bre loss is taken into account, experiment demonstrates that the cross- phase modulation instability gain spectrum is more similar to represent the actual systems. The fibre loss decreases the modulation instability ( MI) gain and has an effect on SNR which is caused by the cross- phase modulation instability. The MI intensity fluctuation caused by the nonlinear and dispersion effects is directly derived. As a result, the initial stage of MI can be described, and the whole characteristic of MI can also be discussed in this way.