设计并实验验证了一种基于双驱马赫-曾德尔调制器(DDMZM)和受激布里渊散射(SBS)窄带光子滤波的新型镜像抑制微波光子混频器结构。将射频(RF)和本振(LO)信号分别输入至DDMZM上下臂的射频端口,控制偏置电压,使得由RF和LO信号所引起的光边带之间满足等效相位调制关系,以抑制由RF同LO光边带拍频产生的带内干扰中频(IF)信号。进一步地,借助SBS损耗谱的窄带光子滤波特性,将有用RF光边带同LO光边带之间的等效相位调制关系转换为强度调制,实现了有用IF信号的产生。实验结果表明:该混频器的镜像抑制比(IRR)可达43dB,在6~20GHz的RF信号以及0.5~1.5GHz的IF信号工作频段,系统的IRR性能可分别保持在35dB~40dB的水平上。

This study proposes and experimentally demonstrates a novel image rejection microwave photonic mixer structure based on a dual-driven Mach-Zehnder modulator (DDMZM) and stimulated Brillouin scattering (SBS) narrow-band photonic filtering. In this structure, the radio frequency (RF) and local oscillator (LO) signals are input to the RF ports of the DDMZM on the upper and lower arms, respectively. The optical sideband caused by the RF and LO signals satisfies the equivalent phase modulation relation by bias voltage control; hence, the in-band interference intermediate frequency (IF) signals generated by the frequency beating of the RF and LO optical sidebands can be rejected. Furthermore, with the narrow-band photonic filtering characteristic of the SBS loss spectrum, a useful IF signal is generated by converting the equivalent phase modulation to the intensity modulation relation between the useful RF and LO optical sidebands. The experimental results show that the image rejection ratio(IRR) of this mixer can reach 43dB. The IRR performance of the system can be maintained at a 35dB--40dB level in the operating frequency band of the 6--20GHz RF signal and the 0.5--1.5GHz IF signal.