NIST researchers used two lasers instead of one to expand the frequency range generated by a microring resonator. The result was a broader chip-scale frequency comb, often described as a miniature optical ruler.

The animation first explains the basic idea of a frequency comb: a set of evenly spaced optical frequencies, like marks on a ruler. It then shows the pulse circulating in the microring as a soliton and uses the waveshape to connect the time-domain picture to the frequency comb output.

The later scenes show how dispersion changes the soliton waveshape. That change broadens the output comb, making the connection between the shape of the circulating pulse and the larger spread of generated frequencies.