Performance evaluation of optical OFDM in direct detected systems based on MZM bias and drive voltages

The impact of DC bias and the RF drive voltage of the dual electrode Mach Zehnder Modulator (DE-MZM) on the transmission performance of optical orthogonal frequency division multiplexing (O-OFDM) direct detected systems is analyzed theoretically and verified by simulation. Selection of optimum bias and drive voltage is necessary to minimize the optical signal to noise ratio (OSNR) requirements and the non-linear distortions in the fiber transmission. In this paper, we compare MZM modulation techniques such as double sideband full carrier and single sideband (SSB) [biased at quadrature and minimum power transmission (MPT) point] with a novel modified SSB OFDM technique. To the best of our knowledge for the first time, a mathematical model for above modified SSB technique is developed to evaluate the OSNR requirement, chromatic dispersion of the fiber, spectral efficiency and the receiver sensitivity against other modulation techniques. Our results show that the modified SSB technique provides high spectral efficiency, receiver sensitivity and low chromatic dispersion against other the modulation techniques, while the one biased at MPT minimizes the OSNR requirements.