Exploiting Ultralow Loss Multimode Waveguides for Broadband Frequency Combs
Exploiting Ultralow Loss Multimode Waveguides for Broadband Frequency Combs
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DOI：
10.1002/lpor.202000353
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发表时间：
2020-12-06
影响因子：
11
通讯作者：
Lipson, Michal
中科院分区：
文献类型：
--
作者：
Ji, Xingchen;Jang, Jae K.;Lipson, Michal
高约束波导中的低传播损耗对于基于芯片的非线性光子学应用是至关重要的。通常需要产生亚纳米粗糙度的复杂制造工艺来减少波导界面处的散射点，以实现超低传播损耗。在这里，超低传播损耗通过使用高度多模结构对模式进行整形以减少其与波导接口的重叠来示出，从而放宽了制造工艺要求。实验证明，微谐振器的固有品质因数（Q）为31.8 +/- 4.4万。虽然微谐振器支持10个横模，但当使用非线性绝热弯曲时，仅激发基模并且没有观察到高阶模。一个创纪录的低阈值泵浦功率为73 μ W的参数振荡测量和宽带，几乎倍频程跨越单孤子频率梳没有任何签名的高阶模式的频谱跨越1097至2040 nm（126太赫兹）中产生的多模微谐振器。这项工作提供了一种设计方法，可以应用到不同的材料平台，以实现和使用超高Q值多模微谐振器。
Low propagation loss in high confinement waveguides is critical for chip-based nonlinear photonics applications. Sophisticated fabrication processes which yield sub-nm roughness are generally needed to reduce scattering points at the waveguide interfaces to achieve ultralow propagation loss. Here, ultralow propagation loss is shown by shaping the mode using a highly multimode structure to reduce its overlap with the waveguide interfaces, thus relaxing the fabrication processing requirements. Microresonators with intrinsic quality factors (Q) of 31.8 +/- 4.4 million are experimentally demonstrated. Although the microresonators support ten transverse modes only the fundamental mode is excited and no higher order modes are observed when using nonlinear adiabatic bends. A record-low threshold pump power of 73 mu W for parametric oscillation is measured and a broadband, almost octave spanning single-soliton frequency comb without any signatures of higher order modes in the spectrum spanning from 1097 to 2040 nm (126 THz) is generated in the multimode microresonator. This work provides a design method that can be applied to different material platforms to achieve and use ultrahigh-Q multimode microresonators.