The impact of group velocity on frequency-hopping optical code division multiple access system

In this paper, we develop a systematic method that employs transfer function considering encoder, fiber channel, and decoder to analyze the frequency-hopping (FH) optical code-division multiple-access (OCDMA) system. We analyze the FH-OCDMA system when both single-mode fiber and dispersion-shifted fiber are employed as the transmission medium. The difference of group velocities affects system performance more seriously than dispersion effect does. The results show that single-mode fiber is not proper for a FH-OCDMA system, even if the transmission length is no more than 1 km. The dispersion-shifted fiber is suitable for a FH-OCDMA system, especially in an access network. We also propose an optical device to compensate the group velocities.