Experimental demonstration of the impact of MZM non-linearity on direct-detection optical OFDM

In this paper, we present experimental demonstrations of the effects on the system performance of a direct-detection optical Orthogonal Frequency Division Multiplexing (DD-OOFDM) system due to variation of the bias voltage to the Mach-Zehnder modulator (MZM). This work also investigates how a variation in the modulation format influences the non-linear distortion introduced by the MZM characteristic and hence the system performance. System performance is evaluated at 3 Gbaud symbol rate using Error Vector Magnitude (EVM) measurements as a performance metric.