Biomedical subjects

U Bortolozzo

Publications and source records attributed to U Bortolozzo.

7 recordsLinked to original sources

PubMed2005

Dissipative solitons driving and bound state control via parameter gradients.

The effect of phase and intensity gradients on the motion of dissipative solitons in a nonlinear interferometer is investigated. We show how the forces exerted by parameter gradients on the solitons alter their interactions. Consequently, it is possible to tune the spectrum of soliton bound states via the introduction of proper spatial distribution of the system parameters. Furthermore, we show how the use of properly shaped parameter distributions can lead to a relevant reduction of the cross-talk between close by solitons in applications.

Interferometry↗

PubMed2004

Bistability between different localized structures in nonlinear optics.

We report the observation of different localized structures coexisting for the same parameter values in an extended system. The experimental findings are carried out in a nonlinear optical interferometer and are fully confirmed by numerical simulations. The existence of each kind of localized structure is put in relation to a corresponding delocalized pattern observed. A quantitative evaluation of the range of pump parameter allowing bistability between localized structures is given. The phenomenon reported results to be robust in parameter space.

Journal Article↗

PubMed2004

Experimental targeting and control of spatiotemporal chaos in nonlinear optics.

We demonstrate targeting and control over spatiotemporal chaos in an optical feedback loop experiment. Different stationary target patterns are stabilized in real time by means of a two dimensional space extended perturbation field driven by an interfaced computer and applied in real space to a liquid crystal display device inserted within a control optical loop. The flexibility of the system in switching between different target patterns is also demonstrated.

Journal Article↗

PubMed2004

Transition to space-time chaos in an optical loop with translational transport.

We describe the transition from regular patterns to space-time chaos in an optical system with nonlocal feedback. The nonlocality introduced breaks the rotational symmetry of the system, resulting in a scenario for the transition from regular patterns to a disordered dynamics. The different regimes are characterized both in terms of spatial and temporal correlation functions, and by means of a Kahrunen-Loeve decomposition. This allows the determination of the structures participating in the dynamics, and an estimation of the active degrees of freedom versus the control parameter.

Journal Article↗

PubMed2003

Control of localized structures in an optical feedback interferometer.

We report a detailed experimental investigation of the dependence of localized structures, observed in a nonlinear optical device, on several control parameters. A first step of the study consists in the determination of the region of existence of localized states as a function of the system variables. Subsequently, we show how different control parameters can be used to the aim of tuning several localized structures properties; among these, of particular relevance are the contrast and the amplitude and frequency of the oscillations appearing on the tails of the structures. A discussion of the relation between the localized states here studied and the one predicted by general model for pattern forming systems is also given.

Biophysical Phenomena↗

PubMed2002

Tailoring the profile and interactions of optical localized structures.

We experimentally demonstrate the broad tunability of the main features of optical localized structures (LS's) in a nonlinear interferometer. By discussing how a single LS depends on the system spatial frequency bandwidth, we show that a modification of its tail leads to the possibility of tuning the interactions between LS pairs, and thus the equilibrium distances at which LS bound states form. This is in agreement with a general theoretical model describing weak interactions of LS in nonlinear dissipative systems.

Journal Article↗

PubMed2001

Experimental evidence for detuning induced pattern selection in nonlinear optics.

We give quantitative experimental evidence of the influence of cavity detuning in determining the pattern selection in a one-dimensional large Fresnel number optical oscillator. The issues of the selection of the transverse mode close to threshold and the value of the pump parameter at threshold are addressed. Competition between right and left traveling waves, resulting in a winner takes all dynamics, is also reported. Experimental results are in quantitative agreement with the theoretical predictions formulated for a broad class of systems comparable to the one here considered.

Journal Article↗