Photonic-Enabled Simultaneous Self-Interference Cancellation and Image Rejection Receiver With Dispersion Immunity Fiber Transmission

A receiver with photonics-enabled simultaneous self-interference cancellation and image rejection for in-band full-duplex communication is proposed and experimentally demonstrated. The carrier suppressed double sideband (CS-DSB) modulation is applied for the conversion of received signals, the reference signal and the local oscillator (LO) signal in optical domain via the dual-polarized quadrature phase shift keying (DP-QPSK) modulator. The sidebands of CS-DSB signals are filtered for photon detection to generate the intermediate frequency (IF) signals. The direct current (DC) biases of the DP-QPSK modulator are utilized to introduce a phase difference of −45° between received signals and the LO signal in the X-polarization to realize the quadrature down-conversion, and a phase difference of 135° between the reference signal and LO signal in Y-polarization to obtain phase inversion for the self-interference cancellation. By regulating the amplitude, phase and time delay of the two polarization CS-DSB signals in optical domain, the image rejection and self-interference cancellation are simultaneously realized in IF band, which has the advantage of dispersion immunity for long fiber transmission. Experimentally, the image and self-interference (SI) are suppressed simultaneously with self-interference cancellation depth of 39, 26, 22 dB and image rejection ratio of 35, 27, 24 dB, corresponding to the bandwidth of 100 MHz, 500 MHz and 1 GHz, respectively. The signal of interest (SOI) with 16-QAM modulation is successfully recovered after 20 km fiber transmission with the SI-to-SOI power ratio of 16.5 dB.