Abstract
Dissipative Kerr cavity solitons (CSs) are persisting pulses of light that manifest themselves in driven optical resonators and that have attracted significant attention over the last decade. Whilst the vast majority of studies have revolved around conditions where the resonator exhibits strong anomalous dispersion, recent studies have shown that solitons with unique characteristics and dynamics can arise under conditions of near-zero-dispersion driving. Here, we report on experimental studies of the existence and stability dynamics of Kerr CSs under such conditions. In particular, we experimentally probe the solitons' range of existence and examine how their breathing instabilities are modified when group-velocity dispersion is close to zero, such that higher-order dispersion terms play a significant role. On the one hand, our experiments directly confirm earlier theoretical works that predict (i) breathing near-zero-dispersion solitons to emit polychromatic dispersive radiation, and (ii) that higher-order dispersion can extend the range over which the solitons are stable. On the other hand, our experiments also reveal a novel cross-over scenario, whereby the influence of higher-order dispersion changes from stabilising to destabilising. Our comprehensive experiments sample soliton dynamics both in the normal and anomalous dispersion regimes, and our results are in good agreement with numerical simulations and theoretical predictions.
Highlights
Temporal Kerr cavity solitons (CSs) are localized pulses of light that can circulate in a driven passive optical resonator without distortion [1,2]
Shown in green is the corresponding curve in the absence of higher-order terms [i.e., βk = 0 for k > 2 and fR = 0], as well as the intensity levels of the homogeneous CW state of the system. (Note that the stability of all the solutions was deduced via a linear stability analysis [42].) We see that, both in the presence and absence of higher-order dispersion terms, the CSs are stable for large detunings, but become unstable through a Hopf bifurcation at detuning H3 and H2, respectively
There is only one discrepancy: A theoretically predicted small island of stability around X = 100 is not observed in our experiment. We suspect this is due to experimental imperfections that prevent access to the small island predicted. (Of note: we have observed the corresponding island in experiments performed for larger values of d3 where the island extends over a larger range of detuning.) Relating to the range of existence, our experiments show good qualitative agreement with numerical predictions, but quantitative discrepancies arise at the low detuning side
Summary
Temporal Kerr cavity solitons (CSs) are localized pulses of light that can circulate in a driven passive optical resonator without distortion [1,2]. There has been growing interest in exploring the dynamics of CSs under conditions of near-zero-dispersion driving, i.e., with the wavelength of the input laser coincident (or close to coincident) with the zero-dispersion wavelength (ZDW) of the resonator. In this regime, higher-order dispersion dominates the dynamics, giving rise to novel bright localized structures both in the normal and anomalous dispersion regimes [33,34,35]. Our results provide significant insights into the dynamics of CSs under conditions of near-zero-dispersion driving and could facilitate the design of broadband frequency combs or novel sources of ultrashort pulse trains
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