Role of Self Phase Modulation and Cross Phase Modulation on Quality of Signal in Optical Links

Abstract

Background: In WDM networks, there is a crucial need to monitor signal degradation factors in order to maintain the quality of transmission. This is more critical in dynamic optical networks as non-linear impairments are network state dependent. Moreover, PLIs are accumulative in nature, so the overall impact is increased tremendously as the length of signal path is increased. The interactions between different impairments along the path also influence their overall impact. Objective: Among the different impairments, the present work focuses on phase modulations owing to the intensities of signals themselves as well as the neighboring signals. It includes the influence of SPM, SPM and XPM, system parameters like signal power, wavelength and fiber parameters like attenuation coefficient, dispersion coefficient and their influence on Q-value and BER. Methods: The analysis is done through a single and two-channel transmitter system with varied power, wavelengths and system parameters. The corresponding optical spectrums are analysed. Results & Conclusion: It has been found that SPM and XPM pose broadening effect on spectrum without any effect on temporal distributions. The magnitude of signal power is among the parameters significantly influencing the broadening of spectrum. The higher the power, the more the magnitude of broadening. It has been found that in order to neglect the impact of input power; its magnitude must be kept below 20 mW. Also, the dispersion and attenuation value need to be carefully as they pose counteracting effect to SPM and XPM for certain values and hence can be used as compensation measures without any additional cost.