Code division multiple access (CDMA) enhancement of wavelength division multiplexing (WDM) systems

Wavelength division multiplexing (WDM) is a mainstream technology for optical communications ranging from long haul applications to interconnections between and within high speed digital systems. WDM is, however, constrained (1) in density by the crosstalk associated with channel spacing and (2) by total number of channels which can be uniformly amplified by optical amplifiers. This number of effective WDM channels can be enhanced by overlaying code division multiple access (CDMA) on each WDM channel. The authors show by analysis and example that the number of effective WDM/CDMA hybrid channels exceeds the number of effective WDM channels, and with a reduced WDM crosstalk penalty