An optical CDMA system based on spectral encoding of LED

A optical code-division multiple access (CDMA) system based on amplitude spectral encoding of low-cost broadband sources such as light-emitting diodes is presented. The proposed system uses a standard nondispersive lens-grating apparatus and simple direct-detection receivers. It is shown that by assigning to N subscribers the N cycles shifts of a single unipolar m-sequence of period N, complete orthogonality between the users can be achieved, provided that the spectrum is properly equalized. It is also shown that without any equalization, and for N=511, up to 200 users can transmit asynchronously with an average error probability equal to 10/sup -9/, depending on the received power level. An aggregate network throughput of 100 Gb/s can therefore be obtained.<>