Low phase noise microwave oscillators are at the center of a multitude of applications that span the gamut of photonics and electronics. Within this space, optically derived approaches to microwave frequency synthesis are particularly compelling owing to their unique combination of ultrawideband frequency access and the potential for resiliency to temperature and environmental perturbation via common-mode noise rejection. We demonstrate here an optical frequency divider that uses the 30 terahertz frequency gap between two stimulated Brillouin scattering (SBS) lasers as the basis for frequency division. The resulting microwave signal, centered at 10 GHz frequency, exhibits exceptionally low phase noise levels of {-}{95}\;{\rm dBc/Hz}${-}{95}\;{\rm dBc/Hz}$ and {-}{110}\;{\rm dBc/Hz}${-}{110}\;{\rm dBc/Hz}$ at 10 Hz and 100 Hz frequency offset, respectively. Moreover, the two SBS lasers, generated from a common fiber resonator, exhibit a high degree of correlated noise cancellation in their frequency difference. We measure 16.1 dB of noise rejection against intentionally applied vibrations, thus showcasing a promising pathway towards portable and robust ultralow noise photonic-microwave synthesis.

中文翻译：

---

通过布里渊谐振器的差频分频合成超低噪声微波

低相位噪声微波振荡器是涵盖光子学和电子学领域的众多应用的核心。在这个领域中，光学衍生的微波频率合成方法特别引人注目，因为它们独特地结合了超宽带频率接入和通过共模噪声抑制对温度和环境扰动具有弹性的潜力。我们在这里演示了一种光学分频器，它使用两个受激布里渊散射 (SBS) 激光器之间的 30 太赫兹频率间隙作为分频的基础。由此${-}{95}\;{\rm dBc/Hz}$产生的微波信号以 10 GHz 频率为中心，在${-}{110}\;{\rm dBc/Hz}$频率偏移分别为 10 Hz 和 100 Hz。此外，由公共光纤谐振器产生的两个 SBS 激光器在频率差方面表现出高度的相关噪声消除能力。我们测量了针对有意施加的振动的 16.1 dB 噪声抑制，从而展示了实现便携式和稳健的超低噪声光子微波合成的有前途的途径。