Defect-engineered ring laser harmonic frequency combs
Defect-engineered ring laser harmonic frequency combs
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DOI：
10.1364/optica.430896
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发表时间：
2021-10-20
期刊：
影响因子：
10.4
通讯作者：
Capasso, Federico
中科院分区：
文献类型：
--
作者：
Kazakov, Dmitry;Opacak, Nikola;Capasso, Federico
在非线性色散光学腔中循环的单色波可能会变成不稳定的结构波形。这种现象被称为调制不稳定性，在光纤激光器、光泵克尔微谐振器以及最近的单片环形量子级联激光器(QCL)中都遇到过。在环形QCL中，这种不稳定性导致了基频梳的产生--光场在每个腔的往返行程中重复一次。在这里，我们展示了同样的不稳定性也可能导致自启动谐波频率梳--每个往返多次重复自己的波形，类似于环形克尔微谐振器中的完美孤子晶体。我们可以通过沿环形波导放置两个微小的缺陷来定制谐波频率梳的模式间间距，这些缺陷之间有明确的间隔。按需激发频率梳状态，其中几个强大的模式间隔数百吉赫兹，可能会在未来的亚太赫兹发电机中使用。由光学学会根据知识共享署名4.0许可证的条款出版。
A monochromatic wave that circulates in a nonlinear and dispersive optical cavity can become unstable and forma structured waveform. This phenomenon, known as modulation instability, was encountered in fiber lasers, optically pumped Kerr microresonators and, most recently, in monolithic ring quantum cascade lasers (QCLs). In ring QCLs, the instability led to generation of fundamental frequency combs-optical fields that repeat themselves once per cavity round trip. Here we showthat the same instability may also result in self-starting harmonic frequency combs-waveforms that repeat themselves multiple times per round trip, akin to perfect soliton crystals in ring Kerr microresonators. We can tailor the inter-mode spacing of harmonic frequency combs by placing two minute defects with a well-defined separation between them along the ring waveguide. On-demand excitation of frequency comb states with few powerful modes spaced by hundreds of gigahertz may find their use in future sub-terahertz generators. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.