Working on All Optical Orthogonal Frequency Division Multiplexing (AO-OFDM) systems to improve performance of these systems. I have investigated the nonlinearity compensating method in AO-OFDM systems, and develop a AO-OFDM system with higher performance toward nonlinearity effects. To obtain better system performance, the influence of dispersion map is investigated on the proposed AO-OFDM system.