213 research outputs found
Complexity in electro-optic delay dynamics: modelling, design and applications
International audienceNonlinear delay dynamics have found during the last 30 years a particularly prolific exploration area in the field of photonic systems. Besides the popular external cavity laser diode set-ups, we focus in this article on another experimental realization involving electro-optic (EO) feedback loops, with delay. This approach has strongly evolved with the important technological progress made on broadband photonic and optoelectronic devices dedicated to high-speed optical telecommunications. The complex dynamical systems performed by nonlinear delayed EO feedback loop architectures were designed and explored within a huge range of operating parameters. Thanks to the availability of high-performance photonic devices, these EO delay dynamics led also to many successful, efficient and diverse applications, beyond the many fundamental questions raised from the observation of experimental behaviours. Their chaotic motion allowed for a physical layer encryption method to secure optical data, with a demonstrated capability to operate at the typical speed of modern optical telecommunications. Microwave limit cycles generated in similar EO delay oscillators showed significantly improved spectral purity thanks to the use of a very long fibre delay line. Last but not least, a novel brain inspired computational principle has been recently implemented physically in photonics for the first time, again on the basis of an EO delay dynamical system. In this latter emerging application, the computed result is obtained by a proper 'read-out' of the complex nonlinear transients emerging from a fixed point, the transient being issued by the injection of the information signal to be processed
Laser Chimeras as a paradigm for multi-stable patterns in complex systems
Chimera is a rich and fascinating class of self-organized solutions developed
in high dimensional networks having non-local and symmetry breaking coupling
features. Its accurate understanding is expected to bring important insight in
many phenomena observed in complex spatio-temporal dynamics, from living
systems, brain operation principles, and even turbulence in hydrodynamics. In
this article we report on a powerful and highly controllable experiment based
on optoelectronic delayed feedback applied to a wavelength tunable
semiconductor laser, with which a wide variety of Chimera patterns can be
accurately investigated and interpreted. We uncover a cascade of higher order
Chimeras as a pattern transition from N to N - 1 clusters of chaoticity.
Finally, we follow visually, as the gain increases, how Chimera is gradually
destroyed on the way to apparent turbulence-like system behaviour.Comment: 7 pages, 6 figure
Delayed Dynamical Systems: Networks, Chimeras and Reservoir Computing
We present a systematic approach to reveal the correspondence between time
delay dynamics and networks of coupled oscillators. After early demonstrations
of the usefulness of spatio-temporal representations of time-delay system
dynamics, extensive research on optoelectronic feedback loops has revealed
their immense potential for realizing complex system dynamics such as chimeras
in rings of coupled oscillators and applications to reservoir computing.
Delayed dynamical systems have been enriched in recent years through the
application of digital signal processing techniques. Very recently, we have
showed that one can significantly extend the capabilities and implement
networks with arbitrary topologies through the use of field programmable gate
arrays (FPGAs). This architecture allows the design of appropriate filters and
multiple time delays which greatly extend the possibilities for exploring
synchronization patterns in arbitrary topological networks. This has enabled us
to explore complex dynamics on networks with nodes that can be perfectly
identical, introduce parameter heterogeneities and multiple time delays, as
well as change network topologies to control the formation and evolution of
patterns of synchrony
Determination of phase noise spectra in optoelectronic microwave oscillators: a Langevin approach
We introduce a stochastic model for the determination of phase noise in
optoelectronic oscillators. After a short overview of the main results for the
phase diffusion approach in autonomous oscillators, an extension is proposed
for the case of optoelectronic oscillators where the microwave is a limit-cycle
originated from a bifurcation induced by nonlinearity and time-delay. This
Langevin approach based on stochastic calculus is also successfully confronted
with experimental measurements.Comment: 18 pages, 7 figures, 11 references. Submitted to IEEE J. of Quantum
Electronics, May 200
Two-dimensional spatiotemporal complexity in dual-delayed nonlinear feedback systems: Chimeras and dissipative solitons
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Chaos 28, 103106 (2018) and may be found at https://doi.org/10.1063/1.5043391.We demonstrate for a photonic nonlinear system that two highly asymmetric feedback delays can induce a variety of emergent patterns which are highly robust during the system’s global evolution. Explicitly, two-dimensional chimeras and dissipative solitons become visible upon a space-time transformation. Switching between chimeras and dissipative solitons requires only adjusting two system parameters, demonstrating self-organization exclusively based on the system’s dynamical properties. Experiments were performed using a tunable semiconductor laser’s transmission through a Fabry-Pérot resonator resulting in an Airy function as nonlinearity. Resulting dynamics were bandpass filtered and propagated along two feedback paths whose time delays differ by two orders of magnitude. An excellent agreement between experimental results and the theoretical model given by modified Ikeda equations was achieved.
Photonic delay systems are of astonishing diversity and have created a rich field of fundamental research and a wide range of applications. Under a transformation from time into pseudo-scape, their basic architecture makes them equivalent to ring networks with perfectly-symmetric coupling. For the first time we extend this spatiotemporal analogy in experiments by adding a second delay, 100 times the length of the first delay line. Nonlinearity is provided by a tunable semiconductor laser traversing a Fabry-Pérot resonator. Visualized in 2D-space, we show the temporal evolution of different chimeras and dissipative solitons. Experimental results excellently agree with numerical simulations of the double-delay bandpass Ikeda equation. Based on the attractors of multiple fixed-point solutions, we provide insight into the mechanism structuring the system’s dynamics.DFG, 163436311, SFB 910: Kontrolle selbstorganisierender nichtlinearer Systeme: Theoretische Methoden und Anwendungskonzept
Virtual Chimera States for Delayed-Feedback Systems
International audienceTime-delayed systems are found to display remarkable temporal patterns the dynamics of which split into regular and chaotic components repeating at the interval of a delay. This novel long-term behavior for delay dynamics results from strongly asymmetric nonlinear delayed feedback driving a highly damped harmonic oscillator dynamics. In the corresponding virtual space-time representation, the behavior is found to develop as a chimeralike state, a new paradigmatic object from the network theory characterized by the coexistence of synchronous and incoherent oscillations. Numerous virtual chimera states are obtained and analyzed, through experiment, theory, and simulations
Complex photonic nonlinear delay dynamics for high performance signal and information processing
International audienceOptoelectronic delayed feedback loops can provide a wide variety of dynamical motions, thanks to their infinite dimensional phase space. When implemented with Telecom grade components, they additionally provide broadband operation, particularly suited for high speed signal and information processing. On the basis on experimental illustration, we will introduce the fundamental nonlinear dynamical properties of photonic delayed feedback systems, from their stable fixed point operation to their high dimensional complex chaotic oscillations, through periodic oscillations. Each of these particular solution will then be further developed to demonstrate advanced information and signal processing capabilities, from secure optical chaos communications at 10Gb/s, to ultra-fast million word per second recognition through neuromorphic computing, through microwave high spectral purity oscillations for radar applications
Optimal nonlinear information processing capacity in delay-based reservoir computers
Reservoir computing is a recently introduced brain-inspired machine learning
paradigm capable of excellent performances in the processing of empirical data.
We focus in a particular kind of time-delay based reservoir computers that have
been physically implemented using optical and electronic systems and have shown
unprecedented data processing rates. Reservoir computing is well-known for the
ease of the associated training scheme but also for the problematic sensitivity
of its performance to architecture parameters. This article addresses the
reservoir design problem, which remains the biggest challenge in the
applicability of this information processing scheme. More specifically, we use
the information available regarding the optimal reservoir working regimes to
construct a functional link between the reservoir parameters and its
performance. This function is used to explore various properties of the device
and to choose the optimal reservoir architecture, thus replacing the tedious
and time consuming parameter scannings used so far in the literature.Comment: 37 pages, 8 figure
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