Simulative investigation of nonlinear distortion in single- and two-tone RoF systems using direct- and external-modulation techniques

In this paper, we investigated a Radio-over-Fiber (RoF) system consisting of two different system set-ups using direct- and external-laser modulation techniques to study frequency response. Further, second- and third-harmonic generations of single- and two-tone RoF systems have been studied. In this work, we also measured the electric Rf power of two receiving channels and BER at received optical power at different modulating Rf frequencies up to 20 GHz using EDFA or SOA amplifiers. The results have been compared for the electric Rf power of receiving channels obtained using a sin2 Mach Zehnder modulator and a linear modulator, and an improvement in the received Rf power with linear modulator in comparison with the sin2 modulator is observed.