基于级联外调制器的六倍频微波信号的光学生成技术研究

Research on the technology of microwave generation with photonic frequency sextupling by cascaded external modulators

提出并实验验证了一种基于级联偏振调制器(PolM)和双平行马赫-曾德尔调制器(DPMZM)的六倍频微波信号的光学生成方法。PolM在射频(RF)信号调制下,会产生多个光边带,通过调节偏振控制器(PC)和检偏器仅获得奇数阶边带,然后通过DPMZM,其中一子MZM调制RF信号,工作在最大传输点(MATP),另一子MZM不调制RF信号,从而抑制掉一阶边带,保留三阶边带,经光电探测器(PD)拍频获得六倍频微波信号。仿真结果表明,在不利用任何光、电滤波器的情况下,调制器消光比为理想状态(100dB)时,RF杂散抑制比(RFSSR)为34dB。即使消光比为非理想状态(30dB)时,生成微波信号的RFSSR仍可以达到21dB。理论分析和实验结果均验证了方案的可行性。

A photonic approach of frequency-sextupling microwave signal generation by cascading a polari- zation modulation （PolM） and a dual-parallel Mach-Zehnder modulator （DPMZM） is theoretically pro- posed and experimentally verified. Optical sidebands are generated under the condition of radio frequency （R_F） signal modulation. By adjusting the polarization controller （PC） before the polarizer and analyzer, only odd-order sidebands are kept. Then going through the DPMZM,one of the sub MZMs is modulated by RF signal,in the maximum transfer point （MATP）. The other sub MZM is not modulated. The first order sidebands are suppressed, so that the third order sidebands are preserved. A frequency sextupling microwave signal can be obtained by beating the two third order siandbands at the photodetector （PD）. The simulation results show that the radio frequency spurious suppression ratio （RFSSR） is as high as 34 dB under the condition of ideal extinction ratio （100 dB） without any optical or electrical filter. Even if the extinction ratio is 30 dB,the RFSSR can still reach 21 dB. Both theoretical analysis and experimen- tal results verify the feasibility of the proposed scheme.