Impact of Chip Shape on the Performance of DS-OCDMA in Presence of GVD and SPM

An analytical approach is presented to investigate the of chip shape-dependent bit error rate (BER) performance of direct sequence optical code division multiple access with cascaded erbium doped fiber amplifiers in presence of fiber optic group velocity dispersion and self phase modulation. In our analysis, super-Gaussian and Hyperbolic-Secant shaped optical orthogonal codes are employed as address sequence. Avalanche photodiode is used for optoelectronic conversion in an optical correlator receiver. The system BER performance is determined on account of receiver, optical amplifier, and multiuser access interference noises. The chip shape-dependent power penalty suffered by the system is evaluated as a function of various parameters at BER of 10-9 for a system operating at 10 Gchip/s. The numerical results indicate that the BER performance of the system is highly dependent on the chip shape and the proposed system performance can be remarkably improved if Hyperbolic-Secant shaped chip is used instead of super-Gaussian shaped chip.