Spectral phase-encoded time-spreading (SPECTS) optical code-division multiple access for terabit optical access networks

This paper discusses design, simulation, and experimental investigations of optical-code-division multiple-access (O-CDMA) networking using a spectral phase-encoded time spreading (SPECTS) method. O-CDMA technologies can potentially provide flexible access of optical bandwidths in excess of 1Tb/s without relying on wavelength- or time-division-multiplexing modules, provided that they overcome the interference caused by other users broadcasting over the same channel, called multiuser interference (MUI). This paper pursues theoretical and experimental methods to mitigate the MUI. Analysis shows that nonuniform phase coding can increase the orthogonality of the code set, thereby reducing the impact of the MUI. The experiment conducted in a SPECTS O-CDMA testbed incorporating a highly nonlinear thresholder demonstrated error-free operation for four users at 1.25-Gb/s/user and for two users at 10-Gb/s/user.