Session DD04: V: Nonlinear Physics and Applications

Time-delay optoelectronic oscillators with nonlinear filters: design, bifurcation analysis and some applications telecommunication

This presentation will show the design, and theoretical and experimental analysis of a time-delay optoelectronic oscillators in which a nonlinear filter is introduced in the electronic branch. It is found that the system produces a very rich dynamics including chaotic behavior characterized by positive maximum Lyapunov exponent and high entropy. We demonstrate that with appropriate values of the system parameters, the unique time delay of the system cannot be traced in its dynamics. Such an advantage is exploited in synchronization using a scheme that confirms the use of the hidden time-delay as a key. Moreover, the high entropy behavior of the system combined with post-processing can be used to generate random numbers for small values of the feedback gain with an overall high bit rate. The theoretical results are in excellent agreement with experimental measurements.   

Chimera states in neuronal networks under the action of an electric field

The phenomenon of the chimera state symbolizes the coexistence of coherent and incoherent sections of a given population. This phenomenon identified in several physical and biological systems presents several variants, including the multichimera states and the traveling chimera state. Here, we numerically study the influence of a weak external electric field on the dynamics of a network of Hindmarsh-Rose (HR) neurons coupled locally by an electrical interaction and nonlocally by a chemical one. We first focus on the phenomena of traveling chimera states and multicluster oscillating breathers that appear in the electric field's absence. Then in the field's presence, we highlight the presence of a chimera state, a multichimera state, an alternating chimera state and a multicluster traveling chimera.   

Sensor sensitivity and synchronization induced by exceptional point in optomechanical systems

We propose an efficient optomechanical mass sensor operating at exceptional points (EPs), non-Hermitian degeneracies where eigenvalues of a system and their corresponding eigenvectors simultaneously coalesce. It consists of two optomechanical cavities that are coupled mechanically. The cavity is driving by a blue-detuned (red-detuned) laser to control the gain loss. At the gain and loss balance, an EP is observed where any perturbation induces a frequency splitting resulting in a giant sensitivity-factor enhancement compared with conventional optomechanical sensors. This work paves the way toward new levels of sensitivity for optomechanical sensors, which could find applications in many other fields, including nanoparticle detection, precision measurement, and quantum metrology.   

Signal amplification and filtering during propagation in a chain of unidirectionnally coupled self-sustained oscillators

This presentation deals with the signal propagation in a chain of self-sustained oscillators coupled unidirectionally having at input sinusoidal and noisy inputs. Different phenomena which appear in the chain include double amplification, chaos and fast filtering phenomenon under certain conditions. Considering a chain with random generation of the natural frequencies of the oscillators, it is found that the disorder reduces the signal amplitude propagating along the chain and induces a coexistence of different dynamical states, namely periodic, quasiperiodic and chaotic states in the chain, which tend to disappear by suitably adjusting the coupling strength. Considering a chirp distribution of frequencies, the signal amplitude is characterized by a parabolic decrease followed by an irregular series of jumps back to a certain value. The obtained results can be applicable in the design of a network of autonomous electrical generators to power micro-mechanical arms for micro-machines.   

On the possibility of rogue waves generation based on the dynamics of the modified Burridge-Knopoff model of earthquake fault and effects of the magma force

We propose a modified Burridge-Knopoff model of earthquake fault, in which two tectonic plates are strongly coupled by nonlinear springs. Depending on the strength of the stick-slip friction force, the system exhibits both stick-slip and damped oscillatory motions and wave profile which fits the Peregrine solution of the damped/forced nonlinear Schrodinger amplitude equation. Our results strongly suggest that rogue waves can emanate from the dynamics of nonlinearly coupled tectonic plates in subduction zones. This is further complemented by the fact that these giant waves were initially observed in Pacific and Atlantic oceans, which play hosts to the world's largest oceanic subduction zones. In the presence of the external influence of magma up flow, we demonstrate that an increase in the magnitude of the magma thrust force can lead to more localized and violent vibrations of earthquake. Results of numerical simulations equally reveal the long-term stability of the modulated seismic waves in a regime of weak damping and magma thrust forces. We suggest that the evolution of modulated seismic waves may serve as a precursor for the occurrence of earthquakes and volcanic eruptions.