Many physical systems display quantized energy states. In optics, interacting resonant cavities show a transmission spectrum with split eigenfrequencies, similar to the split energy levels that result from interacting states in bonded multi-atomic—that is, molecular—systems. Here, we study the nonlinear dynamics of photonic diatomic molecules in linearly coupled microresonators and demonstrate that the system supports the formation of self-enforcing solitary waves when a laser is tuned across a split energy level. The output corresponds to a frequency comb (microcomb) whose characteristics in terms of power spectral distribution are unattainable in single-mode (atomic) systems. Photonic molecule microcombs are coherent, reproducible and reach high conversion efficiency and spectral flatness while operated with a laser power of a few milliwatts. These properties can favour the heterogeneous integration of microcombs with semiconductor laser technology and facilitate applications in optical communications, spectroscopy and astronomy.

许多物理系统显示量子化的能量状态。在光学中，相互作用的谐振腔显示出具有分裂特征频率的透射光谱，类似于键合多原子（即分子）系统中相互作用状态产生的分裂能级。在这里，我们研究了线性耦合微谐振器中光子双原子分子的非线性动力学，并证明当激光在分裂能级上调谐时，该系统支持形成自增强孤立波。输出对应于频率梳（微梳），其功率谱分布特性在单模（原子）系统中是无法实现的。光子分子微梳具有相干性、可重复性，并在以几毫瓦的激光功率运行时达到高转换效率和光谱平坦度。