Optical millimeter-wave signal generation by frequency quadrupling using one dual-drive Mach–Zehnder modulator to overcome chromatic dispersion

Abstract

We propose a novel approach to generate quadrupling-frequency optical millimeter-wave using a dual-drive Mach–Zehnder modulator (MZM) in radio-over-fiber system. By properly adjusting the phase difference in the two modulation arms of MZM, the direct current (DC) bias, the modulation index and the gain of base-band signal, the quadrupling-frequency optical millimeter-wave with signal only carried by one second-order sideband is generated. As the signal is transmitted along the fiber, there is no time shift of the codes caused by chromatic dispersion. Theoretical analysis and simulation results show that the eye diagram keeps open and clear even when the quadrupling-frequency optical millimeter-wave are transmitted over 110km and the power penalty is about 0.45dB after fiber transmission distance of 60km. Furthermore, due to another second-order sideband carrying no signals, a full duplex radio-over-fiber link based on wavelength reuse is also built to simplify the base station. The bidirectional 2.5Gbit/s data is successfully transmitted over 40km standard single mode fiber with less than 0.6dB power penalty in the simulation.