We demonstrated that a single semiconductor laser can produce both an amplitude-modulated and a frequency-modulated frequency comb, revealing a physical relationship between two types of output previously thought to be independent. The physics of the frequency combs is illustrated by an analogy with systems of coupled clocks, first studied by Christiaan Huygens in 1665. The work was done in collaboration with the groups of Benedikt Schwarz (TU Wien) and Stefan Breuer (TU Darmstadt). It was published in Physical Review Letters. Read the synopsis by APS Physics here.