![](https://i0.wp.com/microphotonics.net/wp-content/uploads/2021/01/spectral-extension-1024x652.png?resize=885%2C563)
Broadband frequency combs are a key enabling technology for frequency metrology and spectroscopy. Here, we demonstrate that the spectrum of a soliton microcomb can be extended by bi-chromatic pumping resulting in two combs that synchronize their repetition rate via cross-phase modulation. Read more: Nat Commun 11, 6384 (2020)