Supercontinuum Generation by Polychromatic Soliton Molecules

The particle-like behavior is an outstanding feature of solitons, wherein the existence of soliton molecules can be understood to be an extension of this concept. Such molecules have been shown to exist in dispersion-managed fibers as a result of a balance of attractive and repulsive forces due to the relation of the phases between their constituent solitons [1] . In contrast to these objects the existence of a novel type of heteronuclear, polychromatic molecule states has been shown recently [2] , [3] , for which the underlying binding mechanism is realized by incoherent Kerr interaction. These soliton molecules propagate stably as a single localized state exhibiting interference fringes in the time domain [ Fig. 1(b) ] and constitute of a characteristic ’double-hump’ structure in the frequency domain [ Fig. 1(c) ]. This is in strong contrast to the usual soliton molecule concept. Very recently polychromatic soliton molecules have been experimentally demonstrated in a mode-locked laser [3] and shown to exist in the dissipative Lugiato-Lefever equation [4] . These objects appear promising due to their complex propagation dynamics and intriguing analogies to real molecules, but many of their properties are mostly unknown yet. Here we show the possibility to manipulate the energy redistribution within a molecule and exploit this property to generate supercontinuum spectra. In this novel scheme energy is transferred to a molecule via collision with external solitons in analogy to the collider principle, resembling also a dissociation-like process. After the collision process the molecule state is temporally compressed resulting in the formation of a supercontinuum. In addition, we study the robustness of the polychromatic molecules under perturbation and their binding mechanism in more detail.