In this book, the performance analysis of Optical Code Division Multiple Access (OCDMA) communication systems is studied in terms of Bit Error Rate (BER) versus threshold and BER versus the number of users theoretically and simulation, in case of correlator receivers with/without Optical Hard Limiter (OHL) and chip-level receiver (OOK and M-PPM) in the incoherent OCDMA systems, and study the spectral and temporal phase coherent OCDMA systems.