Stochasticity, periodicity and localized light structures in partially mode-locked fibre lasers

Abstract

Physical systems with co-existence and interplay of processes featuring distinct spatio-temporal scales are found in various research areas ranging from studies of brain activity to astrophysics. The complexity of such systems makes their theoretical and experimental analysis technically and conceptually challenging. Here, we discovered that while radiation of partially mode-locked fibre lasers is stochastic and intermittent on a short time scale, it exhibits non-trivial periodicity and long-scale correlations over slow evolution from one round-trip to another. A new technique for evolution mapping of intensity autocorrelation function has enabled us to reveal a variety of localized spatio-temporal structures and to experimentally study their symbiotic co-existence with stochastic radiation. Real-time characterization of dynamical spatio-temporal regimes of laser operation is set to bring new insights into rich underlying nonlinear physics of practical active- and passive-cavity photonic systems.

Superregular Breathers in Optics and Hydrodynamics: Omnipresent Modulation Instability beyond Simple Periodicity

“…For instance, a continuous wave can be destabilized by weak perturbations leading to the emergence of well-known Turing patterns via modulation instability. But more complex intermittent dynamics with nontrivial periodicity can be observed in distinct configurations of dissipative optical systems [48,49].…”

Unveiling multi-scale laser dynamics through time-stretch and time-lens spectroscopies

“…On the other hand, the bright laser beam, particularly when propagating in well-confined optical fibers with few-micron (μm) core sizes [14], can stimulate intriguing and fruitful nonlinear physics, e.g., Kerr cavity soliton generation [15], ultraweak soliton interaction [16], soliton pairing [17,18] and stochastic dynamics [19][20][21], which has vastly expedited the understanding of nonlinear physics problems spanning over a broad spectrum of disciplines. In extreme cases, furthermore, weak perturbations to the optical oscillators can produce drastic outbursts, e.g., intensive Q-switched mode-locking [22,23] and optical rogue wave (also known as killer wave in oceanography) [24][25][26][27].…”

Real-Time Intensity Domain Characterization of Fibre Lasers Using Spatio-Temporal Dynamics

“…The following sections present the results of application of the spatio-temporal methodology for the case of quasi-CW Raman fibre lasers [32,[56][57][58][59] (Section 3.1), and partially mode locked fibre lasers [33,54,60] (Section 3.2). It is shown how the use of the spatio-temporal methodology helps in the unambiguous identification and discernment between the staggering diversity of lasing regimes in both systems, highlighting the relevance of identification of lasing regimes on the basis of their spatio-temporal dynamics rather than one-dimensional temporal variations of intensity alone.…”

“…Indeed, it can be rescaled into appropriate distance units N × L (or N × 2L, for a Fabry Perot configuration), where L is the physical length of the cavity. Thus, this temporally segmented and collated representation of one-dimensional intensity dynamics is called the spatio-temporal evolution of laser intensity, or simply, spatio-temporal dynamics [32,33] (also see Supplementary, [33]). In a broader context, spatio-temporal representations of intensity dynamics have been employed in describing the dynamic behaviour of semiconductor lasers [34,35] including vertical cavity surface emitting lasers [36,37], transverse pattern formation in various lasers and parametric oscillators [38,39], in the study of multimode instabilities [40][41][42], including those observed in high power fibre lasers [43,44] and in the influence of stimulated Brillouin scattering [45,46].…”