Resonator-enhanced electro-optic (RE-EO) frequency comb generators produce broad combs by coupling an optical field to a resonator containing a phase modulator driven at a harmonic of the resonator free spectral range (FSR). Recent advances in integration technologies have opened up the possibility of fabricating low-loss, efficient, and tunable ring-based RE-EO comb generators. In this work, we analyze the properties of a canonical ring-based RE-EO comb generator and propose a new dual-ring comb generator to increase comb conversion efficiency, an especially important characteristic for comb-based optical communications systems. After a brief review of RE-EO comb generator properties in the case of resonant operation, i.e., when the optical frequency and the modulation frequency are harmonics of the resonator FSR, we analyze the effect of input optical phase noise and modulation phase noise on the resulting comb. Additionally, we show analytically that in non-resonant operation the optical frequency offset and the modulation frequency offset can be much larger than the linewidth of the resonator, increasing the tolerance to fabrication errors. Then, we develop and validate numerical models to predict the output spectrum in the presence of dispersive waveguides, which cannot be modeled analytically. Using these accurate models, we analyze a dual-ring RE-EO comb generator that uses a small coupling ring to increase the conversion efficiency to 32%, compared to the 1.3% efficiency of a single-ring RE-EO comb generator. We then analyze a point-to-point inter-data center optical link and determine that a dual-ring RE-EO comb generator can support high-capacity coherent links at 20 Tb/s per fiber.

中文翻译：

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高效谐振器增强型电光频率梳发生器的设计

谐振器增强型电光 (RE-EO) 频率梳发生器通过将光场耦合到包含以谐振器自由光谱范围 (FSR) 谐波驱动的相位调制器的谐振器来产生宽梳。集成技术的最新进展开辟了制造低损耗、高效和可调谐的基于环的 RE-EO 梳状发生器的可能性。在这项工作中，我们分析了基于标准环的 RE-EO 梳状发生器的特性，并提出了一种新的双环梳状发生器，以提高梳状转换效率，这是基于梳状光通信系统的一个特别重要的特性。在对谐振操作情况下的 RE-EO 梳状发生器特性进行简要回顾后，即当光频率和调制频率是谐振器 FSR 的谐波时，我们分析了输入光相位噪声和调制相位噪声对合成梳的影响。此外，我们分析表明，在非谐振操作中，光学频率偏移和调制频率偏移可能比谐振器的线宽大得多，从而增加了对制造误差的容忍度。然后，我们开发并验证了数值模型，以在存在色散波导的情况下预测输出光谱，而色散波导无法进行分析建模。使用这些精确模型，我们分析了双环 RE-EO 梳状发生器，该发生器使用小型耦合环将转换效率提高到 32%，而单环 RE-EO 梳状发生器的效率为 1.3%。