New architecture for incoherent optical CDMA to achieve bipolar capacity

A simple and efficient method for using bipolar codes in noncoherent optical code-division multiple access systems is proposed. The proposed system requires only incoherent optical delay lines and direct detection receivers. Practical architectures for the encoder/decoder are given. The Letter shows that combining Gold codes of period M=127 and Barker code of period K=4 into composite sequences of period N=508 allows 20 simultaneous active users for P_e=10 ^-9, while requiring only four nonprogrammable delay lines