UWB Monocycle Generation and Bi-Phase Modulation Based on Mach–Zehnder Modulator and Semiconductor Optical Amplifier

We propose and experimentally demonstrate an approach in generating a pair of polarity-reversed ultra-wideband (UWB) monocycle pulses by using a Mach-Zehnder modulator (MZM) and a semiconductor optical amplifier (SOA). The monocycle polarity is controlled by adjusting the bias voltage of the MZM to make the bias point located at the positive or the negative slope of the modulation curve. The generated UWB monocycles with different injection currents of SOA, different bias voltages of MZM, different optical pulse widths, and different optical carrier wavelengths are experimentally studied and analyzed. The bi-phase modulation (BPM) of monocycle pulse by applying nonreturn-to-zero (NRZ) data to the radio frequency (RF) port of MZM is also proposed and investigated.