Qiu Zheru, Singh Neetesh, Liu Yang, Ji Xinru, Wang Rui Ning, Kärtner Franz X, Kippenberg Tobias
Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
Nat Commun. 2025 Jun 6;16(1):5252. doi: 10.1038/s41467-025-59794-z.
Optically generated microwaves exhibit unprecedented low noise, benefiting applications such as communications, radar, instrumentation, and metrology. To date, the purest microwave signals are produced using optical frequency division with femtosecond mode-locked lasers. However, their typical repetition rates of hundreds of MHz require multiplication methods to reach the microwave domain. Here, we introduce a miniaturized photonic integrated circuit-based interleaver, achieving a 64-fold multiplication of the repetition rate from 216 MHz to 14 GHz in Ku-Band. With the interleaver, the generated microwave power was improved by 35 dB, with a phase noise floor reduced by more than 10 folds by alleviating photodetector saturation. Based on a low-loss and high-density SiN waveguides, six cascaded stages of Mach-Zehnder interferometers with optical delay lines up to 33 centimeters long are fully integrated into a compact chip. Our result can significantly reduce the cost and footprint of mode-locked-laser-based microwave generation, enabling field deployment in aerospace and communication applications.
光学产生的微波具有前所未有的低噪声，这有利于通信、雷达、仪器仪表和计量学等应用。迄今为止，最纯净的微波信号是使用飞秒锁模激光器通过光频分频产生的。然而，它们数百兆赫兹的典型重复频率需要乘法方法才能进入微波频段。在此，我们介绍一种基于小型化光子集成电路的交织器，在Ku波段将重复频率从216兆赫兹提高了64倍，达到14吉赫兹。借助该交织器，通过减轻光电探测器饱和，产生的微波功率提高了35分贝，相位噪声本底降低了10倍以上。基于低损耗和高密度的氮化硅波导，六个级联的马赫-曾德尔干涉仪阶段以及长达33厘米的光延迟线被完全集成到一个紧凑的芯片中。我们的成果能够显著降低基于锁模激光器的微波产生的成本和占地面积，从而能够在航空航天和通信应用中进行现场部署。
