A Photonic-Based Wideband RF Self-Interference Cancellation Approach With Fiber Dispersion Immunity

A photonic approach to the cancellation of self-interference in the optical domain with fiber dispersion immunity is proposed. A dual-drive Mach-Zehnder modulator (DD-MZM) in a dual-polarization binary phase-shift keying (DP-BPSK) modulator is used as an optical interference canceller, which cancels the self-interference from the received signal and generates two optical sidebands of the signal of interest (SOI) in the received signal. Another DD-MZM in the DP-BPSK modulator is used to provide a pure optical carrier. By combing the optical signals from the two DD-MZMs and beating them at a photodetector, the SOI can be recovered. In addition, if the SOI needs to be transmitted in optical fiber, the power fading effect caused by fiber dispersion can be overcome by simply introducing a proper phase shift to the pure optical carrier. An experiment is performed. RF self-interference cancellation (SIC) with a bandwidth up to 2 GHz is experimentally demonstrated and a cancellation depth of more than 20 dB is achieved even if the bandwidth of the self-interference is about 2 GHz. The SIC with 25-km fiber transmission and the RF power of the SOI after 25-km fiber transmission are also demonstrated, which proves that the SIC has very good immunity to fiber dispersion and the SOI can be transmitted without power fading.