In this paper, a numerical model of semiconductor optical amplifiers (SOA) is experimentally validated in terms of non-linearity of the SOA, particularly the phase-amplitude coupling factor and four-wave mixing (FWM). This model was then used in a simulation platform of coherent optical OFDM system (CO-OFDM) in the presence of a signal amplified by an SOA having an effective data rate of 10.94 Gb/s. The EVM (Error Vector Magnitude) values obtained by the simulation were validated experimentally for a wide range of powers and wavelengths.