Performance of Fiber Optic MW-OCDMA System in Presence of XPM Effect

In this paper, the performance of multi-wavelength optical code division multiple access (MW-OCDMA) communication system is studied in the presence of fiber nonlinear effect cross-phase modulation (XPM). In a dispersive fiber medium, incomplete collisions occur among the interfering channel signals and the desired channel signal due to XPM causes a frequency shift in the signal resulting in pulse broadening depending on the collision type. The received signal magnitude thus affected due to XPM-induced pulse broadening that facilitates to determine the performance of the proposed system The proposed MW-system is studied by a single-mode fiber operating at 10Gb/s having an avalanche photodiode receiver employing intensity modulation direct detection technique. The receiver noise currents (i.e. bulk dark current, surface leakage current, thermal noise current) and multiple access interferences (MAI) are taken into account to evaluate the system performance. The optical orthogonal code (OOC) is used as an address sequence code for its simplicity. The study is carried out for different system parameters such as fiber length, the number of simultaneous users, interfering pulse power, channel spacing, etc. The results obtained in the present study demonstrate that the system performance severely degrades due to the influence of XPM, although the wider channel spacing improves the system performance significantly.