This paper presents the Monte-Carlo simulation of Optical CDMA (Code Division
Multiple Access) systems, and analyse its performance in terms of the BER (Bit Error
Rate). The spreading sequence chosen for CDMA is Perfect Difference Codes.
Furthermore, this paper derives the expressions of noise variances from first principles
to calibrate the noise for both bipolar (electrical domain) and unipolar (optical domain)
signalling required for Monte-Carlo simulation. The simulated results conform to the
theory and show that the receiver gain mismatch and splitter loss at the transceiver
degrades the system performance