采用了一种基于双平行马赫曾德调制器(DPMZM)产生四倍频微波信号的方法。理论分析了微波四倍频的基本原理,双平行马赫曾德调制器的上臂子MZM加载射频信号, 且上臂子MZM工作在最大传输点, 下臂子MZM直通光载波, 使DPMZM最终工作在载波抑制的偶次边带调制模式,结合光学带通滤波器滤除高阶杂散边带, 提升四倍频信号的纯净度。搭建了基于双平行马赫曾德调制器的四倍频微波光子链路, 并对四倍频系统的性能进行测试,实验结果表明系统的光边带抑制比和射频杂散抑制比分别达到了21.09 dB和28.41 dB。由于链路未引入额外的电子器件, 系统可以产生高达80 GHz的微波信号。基于双平行马赫曾德调制器产生四倍频微波信号的方法结构简单, 易于控制, 具有良好的倍频性能, 可实现高纯净度和高频率的四倍频信号的产生。

A frequency-quadruple microwave signal method based on dual-parallel Mach-Zehnder modulator (DPMZM) was proposed. The frequency-quadruple principle was theoretically analyzed. The upper sub-MZM of the DPMZM was modulated by RF signal and operated at the maximum transmission point (MATP), while only an optical carrier was obtained from the bottom sub-MZM of the DPMZM. Then the DPMZM worked at the carrier-suppressed even-order sideband modulation mode. In order to improve the purity of quadruple frequency signal, optical bandpass filter(OBPF) was used to remove the high-order spurious sideband. Microwave photonic frequency-quadruple system was built based on DPMZM, and its performance was tested experimentally. The results demonstrate that the optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio(RFSSR) can reach 21.09 dB and 28.41 dB, respectively. Since no extra electronic devices were used, the system can generate radio frequency with frequency up to 80 GHz. DPMZM based microwave photonic frequency-quadruple system had the advantages of simple structure, convenient operation and good frequency-quadruple performance, which can realize high purity and high frequency quadruple frequency generation.