Optical-frequency synthesizers, which generate frequency-stable light from a single microwave-frequency reference, are revolutionizing ultrafast science and metrology, but their size, power requirement and cost need to be reduced if they are to be more widely used. Integrated-photonics microchips can be used in high-coherence applications, such as data transmission1, highly optimized physical sensors2 and harnessing quantum states3, to lower cost and increase efficiency and portability. Here we describe a method for synthesizing the absolute frequency of a lightwave signal, using integrated photonics to create a phase-coherent microwave-to-optical link. We use a heterogeneously integrated III–V/silicon tunable laser, which is guided by nonlinear frequency combs fabricated on separate silicon chips and pumped by off-chip lasers. The laser frequency output of our optical-frequency synthesizer can be programmed by a microwave clock across 4 terahertz near 1,550 nanometres (the telecommunications C-band) with 1 hertz resolution. Our measurements verify that the output of the synthesizer is exceptionally stable across this region (synthesis error of 7.7 × 10−15 or below). Any application of an optical-frequency source could benefit from the high-precision optical synthesis presented here. Leveraging high-volume semiconductor processing built around advanced materials could allow such low-cost, low-power and compact integrated-photonics devices to be widely used.An optical-frequency synthesizer based on stabilized frequency combs has been developed utilizing chip-scale devices as key components, in a move towards using integrated photonics technology for ultrafast science and metrology.

中文翻译：

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使用集成光子学的光频合成器

光频合成器从单个微波频率参考产生频率稳定的光，正在彻底改变超快科学和计量学，但如果要更广泛地使用它们，它们的尺寸、功率要求和成本需要降低。集成光子微芯片可用于高相干性应用，例如数据传输 1、高度优化的物理传感器 2 和利用量子态 3，以降低成本并提高效率和便携性。在这里，我们描述了一种合成光波信号绝对频率的方法，使用集成光子学来创建相位相干的微波到光链路。我们使用异构集成的 III-V/硅可调谐激光器，该激光器由在单独的硅芯片上制造的非线性频率梳引导，并由片外激光器泵浦。我们的光频合成器的激光频率输出可以通过 4 太赫兹频率接近 1,550 纳米（电信 C 波段）的微波时钟进行编程，分辨率为 1 赫兹。我们的测量证实合成器的输出在该区域内异常稳定（合成误差为 7.7 × 10−15 或更低）。光频率源的任何应用都可以从这里介绍的高精度光学合成中受益。利用围绕先进材料构建的大容量半导体加工，可以广泛使用这种低成本、低功耗和紧凑的集成光子器件。关键零件，