Dynamics of soliton crystals in optical microresonators

Abstract

Dissipative Kerr solitons in optical microresonators provide a unifying framework for nonlinear optical physics with photonic-integrated technologies and have recently been employed in a wide range of applications from coherent communications to astrophysical spectrometer calibration. Dissipative Kerr solitons can form a rich variety of stable states, ranging from breathers to multiplesoliton formations, among which, the recently discovered soliton crystals stand out. They represent temporally-ordered ensembles of soliton pulses, which can be regularly arranged by a modulation of the continuous-wave intracavity driving field. To date, however, the dynamics of soliton crystals remains mainly unexplored. Moreover, the vast majority of the reported crystals contained defects -missing or shifted pulses, breaking the symmetry of these states, and no procedure to avoid such defects was suggested. Here we explore the dynamical properties of soliton crystals and discover that often-neglected chaotic operating regimes of the driven optical microresonator are the key to their understanding. In contrast to prior work, we prove the viability of deterministic generation of perfect soliton crystal states, which correspond to a stable, defect-free lattice of optical pulses inside the cavity. We discover the existence of a critical pump power, below which the stochastic process of soliton excitation suddenly becomes deterministic enabling faultless, device-independent access to perfect soliton crystals. Furthermore, we demonstrate the switching of soliton crystal states and prove that it is also tightly linked to the pump power and is only possible in the regime of transient chaos. Finally, we report a number of other dynamical phenomena experimentally observed in soliton crystals including the formation of breathers, transitions between soliton crystals, their melting, and recrystallization. arXiv:1903.07122v2 [physics.optics]

Dynamics of soliton self-injection locking in optical microresonators

“…Previous works 23 , 45 have shown that soliton generation occurs in a certain range of the normalized pump detunings ζ , with the lower boundary being above the bistability criterion and the upper boundary being the soliton existence criterion: where is the normalized pump amplitude, ω 0 is the resonance frequency, c is the speed of light, n 2 is the microresonator nonlinear index, P in is the input pump power, n is the refractive index of the microresonator mode, V eff is the effective mode volume, κ is the loaded resonance linewidth, and η is the coupling efficiency ( η = 1/2 for critical coupling). Note, however, that the lower boundary (bistability) includes also a region of breather existence for high pump power 47 , so actual soliton region starts at a bit higher detunings. The linear SIL model 44 predicts that, in the SIL regime, the attainable detuning range of in the locked state does not overlap with the soliton existence range despite the sufficient pump power.…”

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“…Recently, [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] microcombs have attracted significant interest as a fundamentally powerful tool for microwave processing, due to their ability to offer a large number of coherent wavelengths from a single device, thereby increasing the capacity of communications systems [40][41][42], for example. Further, they have enabled the processing of RF spectra for a wide range of advanced signal processing functions as well as neural networks [69][70][71].…”