Synchronous and quasisynchronous optical CDMA with balanced complementary receivers

The use of a balanced complementary receiver in synchronous and quasisynchronous optical code-division multiple access is considered. The structure of the receiver allows the use of bipolar derived codes, which lead to a significant improvement in the maximum number of simultaneous users relative to systems based on conventional receivers with unipolar sequences. In a perfectly synchronous network Walsh-Hadamard or time-shifted m-sequences can be used without causing multiuser interference: while for the quasisynchronous case sequences based on Gold codes, more tolerant to jitter, are proposed. The system is a good candidate for LANs where jitter tolerance allows the implementation of network synchronisation without excessive difficulty.