Cristina M. González, Javier M. Buldú, M. C. Torrent, and Jordi García-Ojalvo Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain Nonlinear Dynamics and Chaos Group, Departamento de Física, Universidad Rey Juan Carlos, Tulipán s/n, 28933 Móstoles, Madrid, Spain Received 30 March 2007; revised manuscript received 11 August 2007; pub...

Hubel and Wiesel (1962) proposed that complex cells in visual cortex are driven by a pool of simple cells with the same preferred orientation but diierent spatial phases. However, a wide variety of experimental results over the past two decades have challenged the pure hierarchical model, primarily by demonstrating that many complex cells receive monosynaptic input from unoriented LGN cells, or...

We study the noise activated dynamics of a model excitable system that consists of a subcritical Hopf oscillator with a time delayed nonlinear feedback. The coherence of the noise driven pulses of the system exhibits a novel double peaked structure as a function of the noise amplitude. The two peaks correspond to separate optimal noise levels for excitation of single spikes and multiple spikes ...

We investigate the dynamics of solitons in generalized Klein-Gordon equations in the presence of nonlinear damping and spatiotemporal perturbations. We will present different mechanisms for soliton explosions. We show (both analytically and numerically) that some space-dependent perturbations or nonlinear damping can make the soliton internal mode unstable leading to soliton explosion. We will ...

We show how to use excitable regimes mediated by localized structures (LSs) to perform AND, OR and NOT logical operations providing full logical functionality. Our scheme is general and can be implemented in any physical system displaying LSs. In particular, LSs in nonlinear photonic devices can be used for all-optical computing applications where several reconfigurable logic gates can be imple...

The frequency dependence of the nonlinear dielectric increment was studied for benzene solutions of the nematogenic molecule 4-(trans-4′-n-hexylcyclohexyl)isothiocyanatobenzene (C6H13CyHx-PhN=C=S, 6CHBT) at 25°C. The increment was induced by a quasi-static electric field of high strength (10 V/m), and its relaxation was detected by an alternating field of low strength (10 V/m) in the frequency ...

We investigate the nonlinearity of a liquid crystal cell doped with gold nanoparticles by considering their selective absorption. Such nonlinearities are promising for optical processing applications and optical limiters. Systems displaying thermal nonlinearities are particularly attractive as the maximum nonlinearity may occur in the absence of an applied field and additionally this nonlineari...

The interaction of light with rotating media has attracted recent interest for both fundamental and applied studies including rotational Doppler shift measurements. It is also possible to obtain amplification through the scattering of light with orbital angular momentum from a rotating and absorbing cylinder, as proposed by Zel'dovich more than forty years ago. This amplification mechanism has ...

We review the generation of the recently predicted multi-component spatial optical solitons in a saturable nonlinear bulk medium. We present numerical simulations for an effectively isotropic model and experimental results for a set of different combinations of a Gaussian beam co-propagating incoherently with a beam of a more complex internal structure, such as a higher order transverse laser m...

We have studied both experimentally and numerically the dynamic effect of nonlinearity on lasing in disordered medium. The third-order nonlinearity not only changes the frequency and size of lasing modes, but also modifies the laser emission intensity and laser pulse width. When the nonlinear response time is longer than the lifetime of the lasing mode, the nonlinearity changes the laser output...