Frequency octupling millimeter wave generated by polarization modulators and distributed by fiber without bit walk-off effect and carrier reuse with pilot

An optical polarization modulator (PoIM) is the key device to generate frequency multiplication millimeter waves (MMW) in the radio over fiber (ROF) system. A novel frequency octupling MMW ROF system is designed. The frequency octupling MMW is generated by beating the ±4th order sidebands, which are generated by a DP-PoIM, in a photodetector. By adopting the composite radio frequency (RF) signal as the PoIM’s RF driving signal, the downlink data can be modulated only on the +4th order optical sideband. The composite RF signal is formed by combining two beam signals: One is the modulated RF driving signal by downlink data with a phase modulator (PM), and the other is the amplified downlink data by the electrical gainer (EG). In the central station, a part of the optical carrier is split out and used as a pilot. In the base station, the pilot is filtered out and used as the uplink optical carrier for carrier reuse. To verify the feasibility of our scheme, the operation principle is analyzed, and a simulation experiment is built. The simulation results are in good agreement with the theoretical analysis. When the key parameters of the devices in the system diverge from their theoretical or default values, their influence on the bit error rate (BER) is also analyzed. Our scheme can effectively overcome the bit walk-off effect caused by optical fiber chromatic dispersion, greatly increase the fiber transmission distance, significantly improve the downlink performance and the tunability of the system. It has important application prospects in MMW ROF systems.