Heteronuclear Soliton Molecules in Optical Microresonators

Abstract

Optical soliton molecules are bound states of solitons that arise from the balance between attractive and repulsive effects. Having been observed in systems ranging from optical fibers to mode-locked lasers, they provide insights into the fundamental interactions between solitons and the underlying dynamics of the nonlinear systems. Here, we enter the multistability regime of a Kerr microresonator to generate superpositions of distinct soliton states that are pumped at the same optical resonance, and report the discovery of heteronuclear dissipative Kerr soliton molecules. Ultrafast electrooptical sampling reveals the tightly short-range bound nature of such soliton molecules, despite comprising dissipative Kerr solitons of dissimilar amplitudes, durations and carrier frequencies. Besides the significance they hold in resolving soliton dynamics in complex nonlinear systems, such heteronuclear soliton molecules yield coherent frequency combs whose unusual mode structure may find applications in metrology and spectroscopy. DISCRETELY PUMPED KERR MICRORESONATORSIn contrast to a conventional monochromatic pumping scheme, here we drive a single resonance with two laser fields, in order to simultaneously generate two distinct arXiv:1901.04026v4 [physics.optics]

Formation and Collision of Multistability-Enabled Composite Dissipative Kerr Solitons

“…1(c)]. One should note that this bichromatically driven multistability is physically distinct from the multistability regime driven in a single resonance by a modulated laser [41], as the modulated light source in the earlier work could not create soliton lattice traps with intracavity potential wells. In contrast, here the solitons are continuously drifting over the minima and maxima of the lattice traps, yet they are able to survive.…”

“…In this work, by simultaneously pumping two optical resonances in the same mode family of a microresonator, we demonstrate that each resonance can be independently driven to its upper or lower stable branch of Kerr bistability [37,38]. As a result, the system can be operated in the regime of multistability, where multiple stable equilibrium states are allowed [39][40][41][42]. This bichromatically pumped multistability allows us to deterministically generate soliton collisions as well as composite solitons [see Fig.…”

“…The DKS examination setup is similar to the one in Ref. [41], which uses an electrical spectrum analyzer (ESA) to monitor the DKS repetition rate f rep and a vector network analyzer (VNA) to measure the transfer function of the Kerr resonator [66][67][68]. The optical spectrum shows that a primary DKS and a secondary DKS coexist, and the transfer function in Fig.…”

“…2(c) and 2(d) for examples. The compositions of constituent DKSs are inferred from the interference patterns [41] of the comb spectra and qualitatively shown in the insets. Despite the coexistence of multiple soliton states giving rise to a kaleidoscope of complex DKS microcomb patterns, there is always only a single repetition rate observed, which suggests that the primary solitons and the secondary solitons are stably bound together when their difference in intrinsic soliton group velocity is relatively small.…”

Coexistence and Interactions between Nonlinear States with Different Polarizations in a Monochromatically Driven Passive Kerr Resonator

“…This implies that, while several CSs can simultaneously coexist [18,34], all of them are expected to exhibit identical characteristics. Recent studies have shown [35,36], however, that this expectation can fail when two (or more) fields with different frequencies drive the resonator: each driving field can then sustain CSs with distinct characteristics. In particular, researchers have used polychromatic driving fields to achieve coexistence between CSs associated with different spatial or polarization mode families of a microresonator [35], achieving compact sources of dual-and even triple-combs.…”