Frequency combs and platicons in optical microresonators with normal GVD

Abstract

We predict the existence of a novel type of the flat-top dissipative solitonic pulses, "platicons", in microresonators with normal group velocity dispersion (GVD). We propose methods to generate these platicons from cw pump. Their duration may be altered significantly by tuning the pump frequency. The transformation of a discrete energy spectrum of dark solitons of the Lugiato-Lefever equation into a quasicontinuous spectrum of platicons is demonstrated. Generation of similar structures is also possible with bi-harmonic, phase/amplitude modulated pump or via laser injection locking.

Coexistence of stable dark- and bright-soliton Kerr combs in normal-dispersion resonators

“…In the absence of TOD, Figure 1(a) shows that a dip in the highintensity HSS A t (red) can evolve into a stable dark soliton (black), while a bump on the low-intensity HSS A b (red) relaxes back to A b . This observation that dark solitons exist, but bright solitons do not, is general [15][16][17]. Reference [16] discussed that dark solitons exist due to the locking of overlapping oscillatory tails in the profile of SWs connecting the upper state A t to the bottom state A b .…”

“…In contrast to the anomalous regime, dark solitons are found in the normal GVD regime, i.e., low-intensity dips embedded in a highintensity homogeneous background. The bifurcation structure and temporal dynamics of these dark solitons, also called "platicons", have been recently studied [15][16][17], and their origin is intimately related to the locking of switching waves (SWs) connecting coexisting homogeneous state solutions of high and low intensity [16][17][18]. Such dissipative localized structures have also been studied in spatial systems, both in one and two dimensions, with different nonlinearities [19,20].…”

Weak Langmuir optical turbulence in a fiber cavity

“…It is thus of fundamental different nature than the conventional dispersive shocks that develop either in the spatial or the temporal domain from coherent disturbances, which have been experimentally observed in ion-acoustic waves [100], water surface gravity waves [101], and fiber optics [102], and have recently regained great interest in optics [103][104][105][106][107][108][109][110][111][112]. Coherent dispersive shocks and their stationary analogues have shown to play a role also in passive cavity configurations [113][114][115], where one can envisage that they can impact the generation of combs in the normal dispersion regime [116,117]. Note that, in the incoherent case examined here, the incoherent shock singularity develops in the cavity well before that it reaches the statistically stationary steady state.…”

Nonlinear Cavity and Frequency Comb Radiations Induced by Negative Frequency Field Effects

“…light sources with a large number of highly resolved and nearly equidistant spectral lines, are attracting a considerable interest in recent years, due to their important applications in metrology, optical clocks, precision spectroscopy, precision time and distance measurements, attosecond pulse generation and complex nonlinear dynamics, to name just a few [1][2][3]. Physical systems that are able to generate KFCs are microring resonators, microtoroids, crystalline resonators, microspheres, photoniccrystal cavities and optical fiber loops [1].…”

“…There is currently an intense research activity aiming to maximise the spectral extent of the comb and its coherence, and to understand the experimentally obtained spectra from first principles. Due to the extremely complex dynamical behaviour and stability properties of the propagating CSs and patterns in the resonators, an intense theoretical activity on the mathematical properties of the traditionally used averaged propagation equation, called the temporal Lugiato-Lefever equation (LLE), has developed over the past years, with a frequent display of new and surprising results [3][4][5][6][7].…”