Capacity and security enhancement in optical CDMA systems

Of all kinds of multiple access techniques, optical code division multiple access (OCDMA) is considered the strongest candidates to challenge the rapid evolution of optical communication systems to support multimedia. However, the harmful multiple access interference (MAI) and all forms of noise such as optical amplified spontaneous emission (ASE) noise, electronic receiver noise and photodiode (PD) shot noise are the limiting factors for the system capacity. The current paper, presents an advanced modulation scheme to enhance the capacity of OCDMA networks using hybrid frequency-polarization shift keying, where the polarization can be utilized to double the communication channel. Moreover, we will adopt the direct detection scheme rather than coherent detection to fulfill (i) the system simplicity, (ii) cost effectiveness, (iii) high immunity to laser noise and (iv) insensitivity to self and cross phase modulations caused by fiber nonlinearity. The simulated computer results for the proposed scheme indicate the substantial enhancement in the performance of the system in terms of “capacity enhancement”. Where, the proposed scheme could mitigate the effect of MAI, and all forms of noise in the network. Moreover, approved its power efficient and provides secure communication.