Spectrally efficient optical CDMA system based on chromatic dispersion for phase coding of individual spectral lines in the time domain

A WDM-compatible spectrally phase encoded-optical CDMA scheme is experimentally demonstrated. The system is based on the use of chromatic dispersion, chosen to achieve a first-order Talbot effect, to obtain a frequency-to-time mapping that allows subsequent coding/decoding of the signal spectrum by applying electro-optic phase modulation in the time domain. Independent coding of each of the spectral lines from a pulsed source is achieved, thus guaranteeing an efficient use of the spectrum. The use of electrooptic modulators to impose the codes enables a simple and rapid reconfiguration of the used codes. Results are given for a system transmitting at 10 Gbps within a 0.7 nm optical window using Hadamard codes.