Two structures that can realise optical single sideband modulation without generating both second order upper and lower sidebands are presented. They are based on a dual-parallel Mach Zehnder modulator (DP-MZM) with an optical filter and a dual-polarisation dual-parallel Mach Zehnder modulator (DPol-DPMZM) with a 90° hybrid coupler. The former is an all-optical structure and hence it has a very wide bandwidth. The latter uses one DP-MZM to realise single sideband suppressed carrier modulation while the other DP-MZM simply passes the optical carrier. It also suppresses the third order sideband on the same side as the wanted fundamental RF modulation sideband. Hence, in an ideal situation, there is no second order harmonic component generated after photodetection. Experimental results are presented for the novel structures, which demonstrate the realisation of optical single sideband modulation without second order sidebands. The results also show large fundamental to second order harmonic power ratio over a wide input RF signal frequency range even after inserting a long single mode fibre into the system for signal transmission. The new optical single sideband modulators find applications in improving the multioctave spurious free dynamic range in a long-haul fibre optic link and reducing measurement errors in an optical vector analyser.

中文翻译：

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用于生成无二阶边带的单射频边带的光子技术


提出了两种可以实现光学单边带调制而不同时产生二阶上边带和下边带的结构。它们基于带有光学滤波器的双并行马赫曾德尔调制器 (DP-MZM) 和带有 90° 混合耦合器的双偏振双并行马赫曾德尔调制器 (DPol-DPMZM)。前者是全光结构，因此具有很宽的带宽。后者使用一个DP-MZM实现单边带抑制载波调制，而另一个DP-MZM简单地传递光载波。它还抑制与所需基本射频调制边带同一侧的三阶边带。因此，在理想情况下，光电检测后不会产生二次谐波分量。给出了新颖结构的实验结果，证明了无需二阶边带的光学单边带调制的实现。结果还表明，即使在将长单模光纤插入系统进行信号传输后，在宽输入射频信号频率范围内基波与二阶谐波功率比也很大。新型光学单边带调制器可用于改善长距离光纤链路中的多倍频程无杂散动态范围以及减少光矢量分析仪中的测量误差。