Song Yunxiang, Hu Yaowen, Lončar Marko, Yang Kiyoul
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
Quantum Science and Engineering, Harvard University, Cambridge, MA, USA.
Light Sci Appl. 2025 Aug 12;14(1):270. doi: 10.1038/s41377-025-01906-x.
Optical frequency combs are indispensable links between the optical and microwave domains. Chip-scale integration promises compact, scalable, and power-efficient frequency comb sources, enabled by the resonantly-enhanced Kerr effect or the electro-optic effect. While combs utilizing the former can reach octave-spanning bandwidths, and combs based on the latter can feature microwave-rate spacings, achieving both features at the same time has been challenging. Here, we simultaneously leverage the strong Kerr and electro-optic effects on thin-film lithium niobate, where dissipative Kerr soliton generation is followed by electro-optic phase modulation, to realize an integrated frequency comb reference with 2,589 lines spaced by 29.308 GHz and spanning 75.9 THz (588 nm). Further, we demonstrate electronic stabilization and control of the comb spacing, naturally facilitated by this approach. The broadband, microwave-rate frequency comb in our work overcomes the spacing-span tradeoff that exists in nonlinear integrated frequency comb sources, paving the way towards chip-scale solutions for next-generation laser spectroscopy, microwave and millimeter wave synthesis, as well as optical communications.
光学频率梳是光域和微波域之间不可或缺的纽带。芯片级集成有望实现紧凑、可扩展且节能的频率梳源，这可通过共振增强克尔效应或电光效应来实现。利用前者的频率梳可实现倍频程跨度的带宽，而基于后者的频率梳可具有微波速率的频率间隔，同时实现这两个特性一直具有挑战性。在此，我们同时利用薄膜铌酸锂上的强克尔效应和电光效应，在产生耗散克尔孤子之后进行电光相位调制，以实现具有2589条谱线、频率间隔为29.308 GHz且跨度为75.9 THz（588 nm）的集成频率梳参考源。此外，我们展示了通过这种方法自然实现的梳齿间隔的电子稳定和控制。我们工作中的宽带、微波速率频率梳克服了非线性集成频率梳源中存在的间隔 - 跨度权衡问题，为下一代激光光谱学、微波和毫米波合成以及光通信的芯片级解决方案铺平了道路。
