BER performance of WDM channels spectrally overlaid with ultrashort pulse CDMA signals in a hybrid optical WDM-CDMA system

Summary form only given. To meet the increasing demands on system capacity in fiber communication networks, it is important to increase the spectral utilization of EDFA bandwidth. We present a novel hybrid optical WDM-CDMA system, where an ultrashort pulse CDMA system based on spectral phase encoding and decoding of coherent pulses is overlaid with an optical WDM scheme in the same spectral region. The broadband CDMA signal allows utilization of some of the optical bandwidth occupied by the guard bands between WDM channels and can be used to provide additional transmission bandwidth for WDM systems already operating at capacity or to support bursty traffic. We present our experimental results on WDM detection at 2.5 Gb/s spectrally overlaid with a broadband 40-Mb/s CDMA channel. Furthermore, we show that our data are in excellent agreement with a simple model predicting the power penalty due to the crosstalk arising from the small fraction of CDMA power within WDM bands. Our model also allows us to discuss scaling of our results to Gb/s CDMA rates.