Tunable frequency combs based on dual microring resonators
Tunable frequency combs based on dual microring resonators
复制标题
DOI：
10.1364/oe.23.021527
复制
发表时间：
2015-08-10
期刊：
影响因子：
3.8
通讯作者：
Lipson, Michal
中科院分区：
文献类型：
--
作者：
Miller, Steven A.;Okawachi, Yoshitomo;Lipson, Michal
为了在微谐振器中实现高效的参数频率梳生成，需要对腔体和总线波导之间的耦合进行外部控制。然而，对于无源单片集成结构，耦合间隙是固定的，无法从外部控制，这使得调整耦合本身就具有挑战性。我们设计了一种双腔耦合微谐振器结构，其中调谐一个环谐振频率会引起整个腔耦合条件的变化。我们通过设计环耦合条件，展示了高效率的宽消光可调性。此外，我们注意到耦合两个路径长度略有不同的腔体会产生明显的色散可调性，并提出了一种模态色散工程的新方法。我们制造的设备由两个耦合的高品质因数氮化硅微谐振器组成，其中谐振的消光比可以使用集成微加热器进行控制。利用这种消光可调性，我们优化了梳状生成效率，并提供了可调谐性以避免高阶模式交叉，这种交叉会降低梳状生成的质量。该器件能够将梳状生成效率提高 110 倍。最后，我们演示了使用低噪声锁相梳状线作为波分复用通道的睁开眼图。 (C) 2015年美国光学学会
In order to achieve efficient parametric frequency comb generation in microresonators, external control of coupling between the cavity and the bus waveguide is necessary. However, for passive monolithically integrated structures, the coupling gap is fixed and cannot be externally controlled, making tuning the coupling inherently challenging. We design a dual-cavity coupled microresonator structure in which tuning one ring resonance frequency induces a change in the overall cavity coupling condition. We demonstrate wide extinction tunability with high efficiency by engineering the ring coupling conditions. Additionally, we note a distinct dispersion tunability resulting from coupling two cavities of slightly different path lengths, and present a new method of modal dispersion engineering. Our fabricated devices consist of two coupled high quality factor silicon nitride microresonators, where the extinction ratio of the resonances can be controlled using integrated microheaters. Using this extinction tunability, we optimize comb generation efficiency as well as provide tunability for avoiding higher-order mode-crossings, known for degrading comb generation. The device is able to provide a 110-fold improvement in the comb generation efficiency. Finally, we demonstrate open eye diagrams using low-noise phase-locked comb lines as a wavelength-division multiplexing channel. (C) 2015 Optical Society of America