Optical domain controlled microwave signal processing technology

Microwave photonic systems process the electrical signal in optical domain so that the characteristics of the output optical signals include the transfer function of the signal processing link. In this paper, we review our recent works about a microwave photonic repeater, self-interference cancellation, and microwave signal coupling techniques. First, based on a photonic repeater consisting of a dual-polarized dual-parallel Mach-Zehnder modulator (DP-DPMZM) and a Polarization Controller (PC), four different down-conversion states can be performed. Two separate Local Oscillator signals (LO) also enable frequency down-conversion of microwave signals in different frequency bands. Secondly, a Dual-Parallel Dual-Drive Mach-Zehnder Modulator (DP-DDMZM) and a low-frequency LO signal source are used to achieve Self-Interference Cancellation and Harmonic Down-Conversion (SIC+HDC) for an In-Band Full-Duplex (IBFD) system. Finally, for the microwave photonic coupling technique, a Photonic Microwave Hybrid Splitter (PMHS) and a Photonic Microwave Hybrid Combiner (PMHC) are proposed, respectively. The PMHS and PMHC individually controls the amplitude and phase of the two signals by adjusting the Direct Current (DC) biases of modulators. Our proposed signal processing techniques are very promising for flexible microwave signal processing, radars, and wireless communications.