Competing Turing and Faraday instabilities in longitudinally modulated passive resonators

We experimentally investigate the interplay of Turing and Faraday (modulational) instabilities in a bistable passive nonlinear resonator. The Faraday branch is induced via parametric resonance owing to a periodic modulation of the resonator dispersion. We show that the bistable switching dynamics is dramatically affected by the competition between the two instability mechanisms, which dictates two completely novel scenarios. At low detunings from resonance switching occurs between the stable stationary lower branch and the Faraday-unstable upper branch, whereas at high detunings we observe the crossover between the Turing and Faraday periodic structures. The results are well explained in terms of the universal Lugiato-Lefever model

Interplay of Polarization and Time-Reversal Symmetry Breaking in Synchronously Pumped Ring Resonators

Optically induced breaking of symmetries plays an important role in nonlinear photonics, with applications ranging from optical switching in integrated photonic circuits to soliton generation in ring lasers. In this work we study for the first time the interplay of two types of spontaneous symmetry breaking that can occur simultaneously in optical ring resonators. Specifically we investigate a ring resonator (e.g. a fiber loop resonator or whispering gallery microresonator) that is synchronously pumped with short pulses of light. In this system we numerically study the interplay and transition between regimes of temporal symmetry breaking (in which pulses in the resonator either run ahead or behind the seed pulses) and polarization symmetry breaking (in which the resonator spontaneously generates elliptically polarized light out of linearly polarized seed pulses). We find ranges of pump parameters for which each symmetry breaking can be independently observed, but also a regime in which a dynamical interplay takes place. Besides the fundamentally interesting physics of the interplay of different types of symmetry breaking, our work contributes to a better understanding of the nonlinear dynamics of optical ring cavities which are of interest for future applications including all-optical logic gates, synchronously pumped optical frequency comb generation, and resonator-based sensor technologies

Local Emergence of Peregrine Solitons: Experiments and Theory

It has been shown analytically that Peregrine solitons emerge locally from a universal mechanism in the so-called semiclassical limit of the one-dimensional focusing nonlinear Schrödinger equation. Experimentally, this limit corresponds to the strongly nonlinear regime where the dispersion is much weaker than nonlinearity at initial time. We review here evidences of this phenomenon obtained on different experimental platforms. In particular, the spontaneous emergence of coherent structures exhibiting locally the Peregrine soliton behavior has been demonstrated in optical fiber experiments involving either single pulse or partially coherent waves. We also review theoretical and numerical results showing the link between this phenomenon and the emergence of heavy-tailed statistics (rogue waves)

Respective prognostic values of germinal center phenotype and early 18fluorodeoxyglucose-positron emission tomography scanning in previously untreated patients with diffuse large B-cell lymphoma

Background and Objectives Diffuse large B-cell lymphomas (DLBCL) have a variable outcome, and powerful methods of prognostication are needed in order to choose the best treatment for each patient. Immunophenotypic classification of the tumor as germinal center (GC) or non-germinal center-like (nGC) and early response evaluation with 18fluorodeoxyglucose positron emission tomography (18FDG-PET) scanning have been correlated with survival in DLBCL but the two methods have never been evaluated simultaneously in the same patient population. Our aim was to investigate their respective prognostic values in the same series of patients.Design and Methods We investigated the expression of CD10, Bcl-6, and MUM1 in 81 patients with DLBCL evaluated early with 18FDG-PET. The tumors were classified as GC or nGC using the algorithm of Hans et al. The results of both methods were correlated with the patients’ characteristics and survival.Results CD10 was positive in 27/76 (36%), Bcl-6 in 43/74 (58%), and MUM1 in 33/73 (45%) interpretable cases. Thirty-eight (51%) were in the GC group, and 36 (49%) in the nGC group. With a median follow-up of 33 months, estimated 3-year event-free survival (EFS) of the whole population was 67%. There was no influence of GC/nGC phenotype on survival. Three-year EFS was 46% in the early PET-positive group versus 80% in the PET-negative group (p=0.0003).Interpretation and Conclusions The prognostic value of GC/nGC phenotype is not confirmed in this heterogeneous series, whereas early PET findings are confirmed to be a powerful predictor of outcome. The impact of treatment decisions based on early PET results should be evaluated

Prediction and manipulation of hydrodynamic rogue waves via nonlinear spectral engineering

Peregrine soliton (PS) is widely regarded as a prototype nonlinear structure capturing properties of rogue waves that emerge in the nonlinear propagation of unidirectional wave trains. It has been recently demonstrated that PS can emerge locally, as an asymptotic structure arising from the propagation of an arbitrary large decaying pulse, independently of its solitonic content. This mathematical discovery has changed the widely accepted paradigm of the solitonic nature of rogue waves by enabling the PS to emerge from partially radiative or even completely solitonless initial data. In this work, we realize this scenario in a water tank experiment with a particular aim to control the point of the PS occurrence in space-time by imposing an appropriately chosen initial chirp. By employing the inverse scattering transform for the synthesis of the initial data, we are able to engineer a localized wave packet with a prescribed solitonic and radiative content. This enabled us to control the position of the emergence of the rogue wave by adjusting the inverse scattering spectrum. The proposed method of nonlinear spectral engineering is found to be robust to higher-order nonlinear effects, preceding the wave breaking dynamics, that are inevitable in realistic wave propagation conditions

Modulation instability in dispersion oscillating fibers

In this review we present recent theoretical and experimental progress on modulation instability and parametric amplification processes in dispersion oscillating fibers. These optical fibers are characterized by longitudinal periodic variations of their outer diameter engineered over the meter-long scale, which provides an additional degree of freedom to the system and leads to the generation of multiple MI sideband pairs. The main results published in single-pass configurations and in passive cavities are summarized in this review

Single-shot observation of breathers from noise-induced modulation instability using heterodyne temporal imaging

We report phase and amplitude measurements of large coherent structures originating from the noise-induced modulation instability in optical fibers. By using a specifically designed time-lens system (SEAHORSE) in which aberrations are compensated, the complex field. is recorded in single-shot over long durations of 200 ps with sub-picosecond resolution. Signatures of Akhmediev breather-like patterns are identified in the ultrafast temporal dynamics in very good agreement with numerical predictions based on the nonlinear Schrodinger equation. (C) 2021 Optical Society of Americ

Progress in nonlinear topographic optical fibers

We investigate basic nonlinear effects in optical fibers which opto-geometrical parameters oscillate along the propagation axis. These “topographic” fibers provide an additional degree of freedom leading to multiple quasi-phase matched modulation instability side lobes in single pass configuration or in passive cavities. Experimental results are confirmed by analytical and numerical ones