基于PDM-DPMZM的大动态范围微波光子I/Q下变频系统

Aiming at the nonlinear distortion problem ignored by most microwave photonic I/Q down-conversion systems, a large dynamic range microwave photonic I/Q down-conversion system based on the polarization division multiplexing dual-parallel Mach-Zehnder modulator (PDM-DPMZM) is proposed. The PDM-DPMZM is used to modulate the radio frequency signal, local oscillator signal, and image signal in parallel. By adjusting the DC bias of the modulator and the powers of the drive signals, the I/Q down-conversion and image interference suppression can be realized. The third-order intermodulation distortion can be suppressed at the same time. Experimental results show that the proposed scheme can achieve an image rejection ratio of more than 44 dB. The spur-free dynamic range can reach 110.5 dB·Hz^4/5. In the 5-20 GHz operating frequency range, the phase imbalance and amplitude imbalance are lower than 0.8° and 0.6 dB, respectively.