Huang S-W, Yang J, Lim J, Zhou H, Yu M, Kwong D-L, Wong C W
Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles, CA, USA.
Optical Nanostructures Laboratory, Center for Integrated Science and Engineering, Solid-State Science and Engineering, and Mechanical Engineering, Columbia University, New York, NY, USA.
Sci Rep. 2015 Aug 27;5:13355. doi: 10.1038/srep13355.
Laser frequency combs are coherent light sources that simultaneously provide pristine frequency spacings for precision metrology and the fundamental basis for ultrafast and attosecond sciences. Recently, nonlinear parametric conversion in high-Q microresonators has been suggested as an alternative platform for optical frequency combs, though almost all in 100 GHz frequencies or more. Here we report a low-phase-noise on-chip Kerr frequency comb with mode spacing compatible with high-speed silicon optoelectronics. The waveguide cross-section of the silicon nitride spiral resonator is designed to possess small and flattened group velocity dispersion, so that the Kerr frequency comb contains a record-high number of 3,600 phase-locked comb lines. We study the single-sideband phase noise as well as the long-term frequency stability and report the lowest phase noise floor achieved to date with -130 dBc/Hz at 1 MHz offset for the 18 GHz Kerr comb oscillator, along with feedback stabilization to achieve frequency Allan deviations of 7 × 10(-11) in 1 s. The reported system is a promising compact platform for achieving self-referenced Kerr frequency combs and also for high-capacity coherent communication architectures.
激光频率梳是一种相干光源，它同时为精密计量提供纯净的频率间隔，并为超快和阿秒科学提供基础。最近，有人提出在高Q微谐振器中的非线性参量转换作为光学频率梳的替代平台，不过几乎所有的频率都在100GHz及以上。在此，我们报道了一种具有与高速硅光电子学兼容的模式间隔的低相位噪声片上克尔频率梳。氮化硅螺旋谐振器的波导横截面被设计成具有小且平坦的群速度色散，使得克尔频率梳包含创纪录的3600条锁相梳状线。我们研究了单边带相位噪声以及长期频率稳定性，并报告了18GHz克尔梳振荡器在1MHz偏移时达到的迄今为止最低的相位噪声本底，为-130dBc/Hz，同时通过反馈稳定实现了1秒内7×10^(-11)的频率阿伦偏差。所报道的系统是实现自参考克尔频率梳以及高容量相干通信架构的一个有前景的紧凑平台。
