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为解决毫米波信号生成中存在的困难,提出了一种基于级联双平行马赫-曾德尔调制器(DPMZM)的16倍频光生毫米波系统。首先通过控制第1个DPMZM的直流偏压、驱动信号相位差和调制指数,完全抑制光载波和±2阶边带,获得±4阶光边带;然后将该光波输入到另一个完全一样的DPMZM,获得±8阶光边带和光载波输出;最后利用光滤波器(OF)滤除光载波,用光电探测器(PD)拍频得到16倍频的毫米波输出。详细分析了系统的工作原理,并通过仿真验证了方案的可行性。当输入射频(RF)驱动信号频率为2.5GHz时,可得到40GHz毫米波输出,并且调制器的调制带宽仅需要2.5GHz。本文方案具有倍频次数高、频谱纯度好等优点。
In order to solve the difficulties in the generation of millimeter-wave signals, a 16-fold optical millimeter-wave system based on cascaded double-parallel Mach-Zehnder modulators (DPMZM) is proposed. First, by controlling the first DPMZM’s DC bias, driving the signal phase difference and modulation index, optical carrier and ± 2 order sidebands are completely suppressed to obtain a ± 4-order optical sideband; then the light wave is input to another exactly the same DPMZM, get ± 8 order optical sideband and optical carrier output; finally use optical filter (OF) to filter out optical carrier, with photodetector (PD) beat frequency to get 16 times the frequency of millimeter wave output. The working principle of the system is analyzed in detail, and the feasibility of the scheme is verified through simulation. When the frequency of the input RF signal is 2.5GHz, a 40GHz millimeter wave output is obtained, and the modulation bandwidth of the modulator only needs 2.5GHz. This scheme has the advantages of high frequency multiplication, good spectral purity and so on.