Sun Wei, Chen Zhiyang, Li Linze, Shen Chen, Yu Kunpeng, Li Shichang, Long Jinbao, Zheng Huamin, Wang Luyu, Long Tianyu, Chen Qiushi, Zhang Zhouze, Shi Baoqi, Gao Lan, Luo Yi-Han, Chen Baile, Liu Junqiu
International Quantum Academy, Shenzhen, 518048, China.
School of Information Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
Light Sci Appl. 2025 Apr 30;14(1):179. doi: 10.1038/s41377-025-01795-0.
Low-noise microwave oscillators are cornerstones for wireless communication, radar and clocks. The employment and optimization of optical frequency combs have enabled photonic microwave synthesizers with unrivalled noise performance and bandwidth breaking the bottleneck of those electronic counterparts. Emerging interest is to use chip-based Kerr frequency combs, namely microcombs. Today microcombs built on photonic integrated circuits feature small size, weight and power consumption, and can be manufactured to oscillate at any frequency ranging from microwave to millimeter-wave band. A monolithic microcomb-based microwave oscillator requires integration of lasers, photodetectors and nonlinear microresonators on a common substrate, which however has still remained elusive. Here, we demonstrate the first, fully hybrid-integrated, microcomb-based microwave oscillator at 10.7 GHz. The chip device, powered by a customized microelectronic circuit, leverages hybrid integration of a high-power DFB laser, a silicon nitride microresonator of a quality factor exceeding 25 × 10, and a high-speed photodetector chip of 110 GHz bandwidth (3 dB) and 0.3 A/W responsivity. Each component represents the state of the art of its own class, yet also allows large-volume manufacturing with low cost using established CMOS and III-V foundries. The hybrid chip outputs an ultralow-noise laser of 6.9 Hz intrinsic linewidth, a coherent microcomb of 10.7 GHz repetition rate, and a 10.7 GHz microwave carrier of 6.3 mHz linewidth - all the three functions in one entity occupying a footprint of only 76 mm. Furthermore, harnessing the nonlinear laser-microresonator interaction, we observe and maneuver a unique noise-quenching dynamics within discrete microcomb states, which offers immunity to laser current noise, suppression of microwave phase noise by more than 20 dB, and improvement of microwave power by up to 10 dB. The ultimate microwave phase noise reaches -75/-105/-130 dBc/Hz at 1/10/100 kHz Fourier offset frequency. Our results can reinvigorate our information society for communication, sensing, imaging, timing and precision measurement.
低噪声微波振荡器是无线通信、雷达和时钟的基石。光频梳的应用和优化使光子微波合成器具备了无与伦比的噪声性能和带宽，突破了电子同类产品的瓶颈。目前人们越来越关注基于芯片的克尔频率梳，即微梳。如今，基于光子集成电路构建的微梳具有体积小、重量轻、功耗低的特点，并且可以制造为在从微波频段到毫米波频段的任何频率下振荡。基于单片微梳的微波振荡器需要在同一衬底上集成激光器、光电探测器和非线性微谐振器，然而这一点仍然难以实现。在此，我们展示了首个工作在10.7 GHz的全混合集成、基于微梳的微波振荡器。该芯片器件由定制的微电子电路供电，利用了高功率分布反馈（DFB）激光器、品质因数超过25×10的氮化硅微谐振器以及带宽为110 GHz（3 dB）、响应度为0.3 A/W的高速光电探测器芯片的混合集成。每个组件都代表了其所属类别中的先进水平，同时还能使用成熟的互补金属氧化物半导体（CMOS）和化合物半导体（III-V）代工厂进行低成本的大规模制造。该混合芯片输出本征线宽为6.9 Hz的超低噪声激光器、重复频率为10.7 GHz的相干微梳以及线宽为6.3 mHz的10.7 GHz微波载波——这三种功能集成于一个实体中，占地面积仅为76 mm。此外，利用非线性激光 - 微谐振器相互作用，我们在离散微梳状态下观察并操控了一种独特的噪声抑制动力学，它能抵御激光电流噪声，将微波相位噪声抑制超过20 dB，并将微波功率提高多达10 dB。在1/10/100 kHz傅里叶偏移频率下，最终的微波相位噪声达到 -75/-105/-130 dBc/Hz。我们的成果可为通信、传感、成像、计时和精密测量等信息社会领域注入新的活力。
