Impact of nonlocal interactions in dissipative systems: towards minimal-sized localized structures

In order to investigate the size limit on spatial localized structures in a nonlinear system, we explore the impact of linear nonlocality on their domains of existence and stability. Our system of choice is an optical microresonator containing an additional metamaterial layer in the cavity, allowing the nonlocal response of the material to become the dominating spatial process. In that case, our bifurcation analysis shows that this nonlocality imposes a new limit on the width of localized structures going beyond the traditional diffraction limit.Comment: 4 pages, 4 figure

Measuring the nonlinear refractive index of graphene using the optical Kerr effect method

© 2016 Optical Society of America.By means of the ultrafast optical Kerr effect method coupled to optical heterodyne detection (OHD-OKE), we characterize the third-order nonlinear response of graphene and compare it to experimental values obtained by the Z-scan method on the same samples. From these measurements, we estimate a negative nonlinear refractive index for monolayer graphene, n2 = -1.1 × 10-13 m2/W. This is in contradiction to previously reported values, which leads us to compare our experimental measurements obtained by the OHD-OKE and the Z-scan method with theoretical and experimental values found in the literature and to discuss the discrepancies, taking into account parameters such as doping

Negative diffraction pattern dynamics in nonlinear cavities with left-handed materials

We study a ring cavity filled with a slab of a right-handed material and a slab of a left-handed material. Both layers are assumed to be nonlinear Kerr media. First, we derive a model for the propagation of light in a left-handed material. By constructing a mean-field model, we show that the sign of diffraction can be made either positive or negative in this resonator, depending on the thicknesses of the layers. Subsequently, we demonstrate that the dynamical behavior of the modulation instability is strongly affected by the sign of the diffraction coefficient. Finally, we study the dissipative structures in this resonator and reveal the predominance of a two-dimensional up-switching process over the formation of spatially periodic structures, leading to the truncation of the homogeneous hysteresis cycle.Comment: 8 pages, 5 figure

Comparing endovenous laser ablation, foam sclerotherapy, and conventional surgery for great saphenous varicose veins

BackgroundMany case series have been published on treatments of varicose veins, but comparative randomized controlled trials remain sparse.ObjectiveTo compare the anatomic success rate, frequency of major complications, and quality-of-life improvement of endovenous laser ablation (EVLA), ultrasound-guided foam sclerotherapy (UGFS), and conventional surgery (CS), after 1-year follow-up.MethodsA total of 240 consecutive patients with primary symptomatic great saphenous vein reflux were randomized to EVLA, UGFS, or CS, consisting of high ligation and short stripping. Primary outcome was anatomic success defined as obliteration or absence of the treated vein on ultrasound examination after 1 year. Secondary outcomes were complications, improvement of the “C” class of the CEAP classification, and improvement of disease-specific (Chronic Venous Insufficiency Quality-of-Life Questionnaire) and general (EuroQol 5) quality-of-life scores.ResultsMore than 80% of the study population was classified as C2 or C3 venous disease. After 1 year, the anatomic success rate was highest after EVLA (88.5%), followed by CS (88.2%) and UGFS (72.2%) (P < .001). The complication rate was low and comparable between treatment groups. All groups showed significant (P < .001) improvement of EuroQol 5 and Chronic Venous Insufficiency Quality-of-Life Questionnaire scores after therapy; 84.3% of all treated patients showed an improvement of the “C” of the CEAP classification.ConclusionsAfter 1-year follow-up, EVLA is as effective as CS and superior to UGFS according to occlusion on ultrasound duplex. Quality of life improves after treatment in all groups significantly

Spatial fluctuations of optical solitons due to long-range correlated dielectric perturbations in liquid crystals

Starting from the de Gennes theory of director fluctuations in nematics, we report on a model of the spatial fluctuations in nematicon propagation. We demonstrate that, when the long-range correlation that characterizes nematic liquid crystals is taken into account in the thermal noise, it is possible to account for the spatial oscillations and propagation losses experienced by nematicons. Increasing the power of the nematicon, the oscillation amplitudes increase and the propagation losses decrease. The nematicon is then more strongly confined and deviates more, but is less scattered by the thermally induced perturbations of the refractive index. All the results are in good agreement with the experimental observation

Self-spectrotemporal imaging of nonlinear-dispersive similariton

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