Impact of optical fiber dispersion and self phase modulation on the performance of DS-OCDMA

The performance of direct sequence optical code division multiple access with cascaded optical amplifiers is analytically investigated in presence of fiber group velocity dispersion (GVD) and self phase modulation (SPM). In our analysis, Gaussian-shaped optical orthogonal codes are employed as address sequence and avalanche photodiode is used in an optical correlator receiver. The signal to noise power for the proposed system is evaluated on account of receiver, optical amplifier and multiuser access interference noises. The system performance is determined as a function of optical signal power, code length, code weight, number of simultaneous users, and fiber length. The power penalty suffered by the system is evaluated at bit error rate (BER) of 10^-9. The numerical results show that the BER performance of the system is highly dependent on the signal input power, bit rate, and fiber length. It is found that the performance of the proposed system can be improved by the combined effect of GVD and SPM.