Optical RF Self-Interference Cancellation Using Polarization Multiplexed Dual-MZMs

An optical approach to cancel the RF self-interference using polarization multiplexed Mach-Zehnder modulators (MZMs) is presented with theoretical analysis and experimental demonstration. By using the dual-MZMs biased at inverted quadrature points, the out of phase relationship between the received interference signal and the reference signal is obtained. Through adjusting the delay time and amplitude of the reference signal in optical domain, the matching conditions for the RF self-interference cancellation are implemented. Only one laser source is utilized and the coherent beat noise between the optical carriers from the same laser source is prevented by the polarization multiplexing. The cancellation experiments of RF signals at 5 GHz and 8 GHz are conducted. The self-interference cancellation performance for single frequency and bandwidth of 5 MHz and 10 MHz are investigated.