Multi-Octave Linearization and Self-Interference Cancellation Based on Photonics

A multi-octave linearized self-interference cancellation (SIC) scheme is proposed in this paper. A Polarization-multiplexing Dual-parallel Mach-Zehnder Modulator (PM-DPMZM) is used. Each sub-DPMZM realizes the SIC, through applying the received signal and the reference signal to the sub-MZMs biased at the quadrature and minimum points respectively. The phase inversion between the reference signal and the self-inference signal is achieved by adjusting the biasing voltage of the parent MZM of the DPMZM. Since the received RF signal is divided by a 90° electrical hybrid, the optically carried RF signals with a 90-degree phase difference are output from the two sub-DPMZMs, respectively. By adjusting the angle of the polarizer after the PM-DPMZM, the second-order intermodulation distortion (IMD2), the second-order harmonic distortion (SHD) and third-order intermodulation distortion (IMD3) can be eliminated at the output of the photodetector (PD). Thus, the multi-octave linearized self-interference cancellation is achieved. Theoretical analyses and simulations are taken.