近日，美国加州理工学院Marandi, Alireza团队研究了纳米光子铌酸锂的拓扑孤子频率梳。相关论文于2026年3月25日发表在《自然》杂志上。
频率梳已彻底改变了计量学、测距和光学时钟领域，这极大地推动了芯片级频率梳光源的研发。目前已有一些片上频率梳光源，并通过电光调制、锁模激光器、量子级联激光器或基于克尔非线性的孤子产生等方式得以实现。然而，片上频率梳光源的广泛应用仍面临挑战，因为它们依然依赖射频源、高品质因子（高Q值）谐振腔或复杂的稳频方案，同时还面临效率方面的难题。
研究组展示了一种通过将铌酸锂纳米光子电路与半导体激光器集成实现的片上频率梳光源，该方案有望缓解上述挑战。他们展示了在具有二次非线性和低细度的片上纳米光子参量振荡器中形成时间拓扑孤子的过程。这些孤子与色散状态无关，由相位缺陷构成，这些缺陷将信号频率处（为输入泵浦频率的一半）两个相位相差π的连续波解分隔开。
研究组利用片上互相关进行时间测量，证实了在2 μm附近形成了短至60 fs的拓扑孤子，这与广义参量驱动金兹堡-朗道理论相符。此外，他们还演示了一种混合集成拓扑频率梳光源的概念验证型“一键式”操作。拓扑孤子有望用于开发集成频率梳光源，这类光源与色散特性无关，无需高Q值谐振腔或高速调制器，并可实现难以触及的光谱区域（包括中红外区域）的应用。
附：英文原文
Title: Topological soliton frequency comb in nanophotonic lithium niobate
Author: Englebert, Nicolas, Gray, Robert M., Ledezma, Luis, Sekine, Ryoto, Zacharias, Thomas, Ramesh, Rithvik, Gutierrez, Benjamin K., Parra-Rivas, Pedro, Marandi, Alireza
Issue&Volume: 2026-03-25
Abstract: Frequency combs have revolutionized metrology, ranging and optical clocks1, motivating substantial efforts on the development of chip-scale comb sources2,3. Some on-chip comb sources exist and have been implemented through electro-optic modulation4,5, mode-locked lasers6,7, quantum cascade lasers8,9,10 or soliton formation by Kerr nonlinearity11,12. However, widespread deployment of on-chip comb sources has remained elusive, as they still require radiofrequency sources, high-Q (high-quality factor) resonators or complex stabilization schemes while facing efficiency challenges. Here, we demonstrate an on-chip frequency comb source based on the integration of a lithium niobate nanophotonic circuit with a semiconductor laser that can alleviate these challenges. We show the formation of temporal topological solitons in an on-chip nanophotonic parametric oscillator with quadratic nonlinearity and low finesse. These solitons, independent of the dispersion regime, consist of phase defects separating two π-out-of-phase continuous wave solutions at the signal frequency, which is half the input pump frequency13,14. We use on-chip cross-correlation for temporal measurements and confirm formation of topological solitons as short as 60fs around 2μm, in agreement with a generalized parametrically forced Ginzburg–Landau theory15,16,17. Moreover, we demonstrate a proof-of-concept turn-key operation of a hybrid-integrated source of topological frequency comb. Topological solitons are potential candidates for the development of integrated comb sources, which are dispersion-sign agnostic and do not require high-Q resonators or high-speed modulators, and can provide access to hard-to-reach spectral regions, including mid-infrared regions18.
DOI: 10.1038/s41586-026-10292-2