Influence of Single-mode Fiber Dispersion and Pulse Linear Chirp on Direct-detection Optical CDMA Systems

摘要

In this paper, the influence of single-mode fiber (SMF) dispersion and pulse linear chirp on direct-detection optical code-division multiple-access (OCDMA) systems is analyzed. In the analysis, optical orthogonal codes (OOCs) are employed as address sequence codes. Avalanche photodiode (APD) is selected as the system receiver. The effect of APD shot noise, bulk dark current, surface leakage current, thermal noise current and multiuser access interference (MAI) is considered. The loss of system devices is omitted. The system performance is evaluated under the assumption of optical signal power, code length and code weight are constant. The numerical results show that, if the effect of SMF dispersion is considered, the system performance, i.e., bit error rate (BER) is degradation. With pulse width decreasing and transmission distance increasing, the system performance becomes aggravation. Also, the pulse linear chirp has an important effect on the system BER performance.