Optical CDMA using balanced detection and optical hard-limiters

In this paper, we utilize optical hard-limiters to further enhance the system performance in balanced detection optical CDMA systems. It had been investigated that balanced detection is not superior to the OOK scheme because of the impact of beat noise. The employment of optical hard-limiter is an effective way to completely alleviate the adverse impact of beat noise. The carrier-hopping prime code is utilized as signature sequences whose out of phase autocorrelation is zero and the cross-correlation is at most one. Due to the orthogonality of signature sequence, the correlator of shifted version of carrier-hopping prime code is utilized in the receiver. The numerical results reveal that our proposed scheme can greatly reduce the error floor; also it is superior to that of using OOK scheme with optical hard-limiter.