Optical soliton molecules are under intense research focus, owing in particular to the interesting analogies between their self-assembly and internal dynamics, and those of matter molecules. Two interacting dissipative solitons can form a soliton-pair molecule, which can behave as a robust entity traveling around the cavity for an indefinite time [1]. The internal oscillatory dynamics of soliton molecules can be compared to molecular vibrations, though they are fundamentally different [2,3]. The recent experimental investigations in Refs. [2,3] have been enabled by the dispersive Fourier transform (DFT) technique, which allows recording spectral measurements at multi-MHz frame rates. They showed the existence of various oscillatory dynamics among soliton-pair and soliton-triplet basic molecules. © 2019 IEEE