Papers by Alessandro Scirè
Optics letters, 2002
We report on fabrication and characterization of single-longitudinal- and transverse-mode semicon... more We report on fabrication and characterization of single-longitudinal- and transverse-mode semiconductor ring lasers. A bifurcation from bidirectional stable operation to a regime with alternate oscillations of the counterpropagating modes was observed experimentally and is theoretically explained through a two-mode model. Analytical expressions for the onset and the frequency of the oscillations are derived, and L-I curves numerically evaluated. Good quantitative agreement between theory and measurements made over a large number of tested devices is obtained.
PLoS ONE, 2017
In this work we show how global self-organized patterns can come out of a disordered ensemble of ... more In this work we show how global self-organized patterns can come out of a disordered ensemble of point oscillators, as a result of a deterministic, and not of a random, cooperative process. The resulting system dynamics has many characteristics of classical thermodynamics. To this end, a modified Kuramoto model is introduced, by including Euclidean degrees of freedom and particle polarity. The standard deviation of the frequency distribution is the disorder parameter, diversity, acting as temperature, which is both a source of motion and of disorder. For zero and low diversity, robust static phase-synchronized patterns (crystals) appear, and the problem reverts to a generic dissipative many-body problem. From small to moderate diversity crystals display vibrations followed by structure disintegration in a competition of smaller dynamic patterns, internally synchronized, each of which is capable to manage its internal diversity. In this process a huge variety of self-organized dynami...
Optical and Quantum Electronics, 2020
We propose a new telemeter scheme for absolute distance measurements, based on a semiconductor ri... more We propose a new telemeter scheme for absolute distance measurements, based on a semiconductor ring laser, working in the bistability regime. The optical feedback provided by two external reflectors (a fixed one at short distance, and a moveable one defining the measuring arm) generates commutations of the propagation direction (clockwise, counter-clockwise) inside the ring laser, the period of which is linearly related to the distance of the measure arm reflector. A convenient electrical output signal can be easily obtained by a photodiode located behind the (partially reflecting) fixed mirror. This telemeter, which combines time-of-flight and optical injection, is very simple to implement, since, in addition to the laser, it only requires mirrors and collimation or focusing optics. Also electronic driving and processing are straightforward. Differently from most time-of-flight telemeters, this scheme does not require special provisions or processing to tackle the ambiguity problem...
The dynamic behavior of a semiconductor ring laser
We review theoretical results on the dynamics of solitary single longitudinal mode and single tra... more We review theoretical results on the dynamics of solitary single longitudinal mode and single transversal mode semiconductor ring lasers. These analyses are based on a rate equation model for the slowly varying envelopes of the counter-propagating fields in the ring cavity which has been proposed by Sorel et al. [Opt. Lett. 27, 1992 (2002); IEEE J. Quantum Electron. 39, 1187 (2003)]. The model shows several operating regimes. The lasers are found to operate bidirectionally up to twice the threshold, where unidirectional operation starts. Just above threshold, the lasers operate in a regime where the two counterpropagating modes are continuous wave, while as the injected current is increased, a regime appears where the intensities of the two counterpropagating modes undergo alternate sinusoidal oscillations. To understand these dynamical features, we discuss a reduction of this basic rate equation model derived by Van der Sande et al. [accepted for publication in J. Phys. B (2008)]. ...
We introduce a prototype model for globally-coupled oscillators in which each element is given an... more We introduce a prototype model for globally-coupled oscillators in which each element is given an oscillation frequency and a preferential oscillation direction (polarization), both randomly distributed. We found two collective transitions: to phase synchronization and to polarization ordering. Introducing a global-phase and a polarization order parameters, we show that the transition to global-phase synchrony is found when the coupling overcomes a critical value and that polarization order enhancement can not take place before global-phase synchrony. We develop a self-consistent theory to determine both order parameters in good agreement with numerical results.
Applied Physics Letters, 2008
We have experimentally and theoretically analyzed the modal properties of semiconductor ring lase... more We have experimentally and theoretically analyzed the modal properties of semiconductor ring lasers and the wavelength jumps that occur in connection with directional switching above the threshold.
IEEE Journal of Quantum Electronics, 2003
Theory and experiments of single-mode ridge waveguide GaAs-AlGaAs semiconductor ring lasers are p... more Theory and experiments of single-mode ridge waveguide GaAs-AlGaAs semiconductor ring lasers are presented. The lasers are found to operate bidirectionally up to twice the threshold, where unidirectional operation starts. Bidirectional operation reveals that just above threshold, the lasers operate in a regime where the two counterpropagating modes are continuous wave. As the injected current is increased, a new regime appears where the intensities of the two counterpropagating modes undergo alternate sinusoidal oscillations with frequency in the tens of megahertz range. The regime with alternate oscillations was previously observed in ring lasers of the gas and dye type, and it is here reported and investigated in semiconductor ring lasers. A theoretical model based on a mean field approach for the two counterpropagating modes is proposed to study the semiconductor ring laser dynamics. Numerical results are in agreement with the regime sequence experimentally observed when the injec...
IEEE Journal of Quantum Electronics, 1997
We propose a new scheme for synchronization of the optical chaos generated by a semiconductor las... more We propose a new scheme for synchronization of the optical chaos generated by a semiconductor laser subjected to external reflection. The scheme is based on optical feedback and will be analyzed from the viewpoint of static and dynamic properties and of robustness to external perturbations and noise. An application to cryptographic communications (chaotic shift keying) is finally proposed.
IEEE Journal of Quantum Electronics, 1998
In this paper, we analyze the phenomena arising when a monomode semiconductor laser is subjected ... more In this paper, we analyze the phenomena arising when a monomode semiconductor laser is subjected to external injection from another laser. The system stability is investigated as a function of detuning and of the relative injected power. Different regimes, spanning from phase locking to chaos and coherence collapse, are described by analytical and numerical methods for weak and moderate injection. Previous theoretical studies are extended by describing the inverse transition from chaos to stability and by deriving the final locking condition. Also, further investigation on the coherence collapse regime has been performed. Besides contributing to the exploration of an interesting fundamental phenomenon, the results of this analysis are useful for different applications, including coherent detection and chaotic cryptography.
Optics Express, 2007
Semiconductor ring lasers display a variety of dynamical regimes originating from the nonlinear c... more Semiconductor ring lasers display a variety of dynamical regimes originating from the nonlinear competition between the clockwise and counter-clockwise propagating modes. In particular, for large pumping the system has a bistable regime in which two stationary quasi-unidirectional counter-propagating modes coexist. Bistability is induced by cross-gain saturation of the two counter-propagating modes being stronger than the self-saturation and can be used for data storage when the semiconductor ring laser is addressed with an optical pulse. In this work we study the response time when an optical pulse is injected in order to make the system switch from one mode to the counter-propagating one. We also determine the optimal pulse energy to induce switching.
European Quantum Electronics Conference, Jun 22, 2003
Physical Review E, Jan 9, 2007
Large variety of physical, chemical, and biological systems show excitable behavior, characterize... more Large variety of physical, chemical, and biological systems show excitable behavior, characterized by a nonlinear response under external perturbations: only perturbations exceeding a threshold induce a full system response ͑firing͒. It has been reported that in coupled excitable identical systems noise may induce the simultaneous firing of a macroscopic fraction of units. However, a comprehensive understanding of the role of noise and that of natural diversity present in realistic systems is still lacking. Here we develop a theory for the emergence of collective firings in nonidentical excitable systems subject to noise. Three different dynamical regimes arise: subthreshold motion, where all elements remain confined near the fixed point; coherent pulsations, where a macroscopic fraction fire simultaneously; and incoherent pulsations, where units fire in a disordered fashion. We also show that the mechanism for collective firing is generic: it arises from degradation of entrainment originated either by noise or by diversity.
Arxiv preprint physics/0403038, 2004
We analyze a system of globally coupled limit-cycle oscillators, considering the polarization deg... more We analyze a system of globally coupled limit-cycle oscillators, considering the polarization degree of freedom, and including randomly distributed natural frequencies and oscillation angles. Increasing the coupling from zero, no polarization order enhancement ...
Theory in Biosciences, 2023
This work concerns a many-body deterministic model that displays lifelike properties as emergence... more This work concerns a many-body deterministic model that displays lifelike properties as emergence, complexity, self-organization, spontaneous compartmentalization, and self-regulation. The model portraits the dynamics of an ensemble of locally coupled polar phase oscillators, moving in a two-dimensional space, that in certain conditions exhibit emergent superstructures. Those superstructures are self-organized dynamic networks, resulting from a synchronization process of many units, over length scales much greater than the interaction length. Such networks compartmentalize the twodimensional space with no a priori constraints, due to the formation of porous transport walls, and represent a highly complex and novel non-linear behavior. The analysis is numerically carried out as a function of a control parameter showing distinct regimes: static, stable dynamic networks, intermittency, and chaos. A statistical analysis is drawn to determine the control parameter ranges for the various behaviors to appear. The model and the results shown in this work are expected to contribute to the field of artificial life.
Theory in Biosciences 142, 291–299 , 2023
This work concerns a many-body deterministic model that displays lifelike properties as emergence... more This work concerns a many-body deterministic model that displays lifelike properties as emergence, complexity, self-organization, spontaneous compartmentalization, and self-regulation. The model portraits the dynamics of an ensemble of locally coupled polar phase oscillators, moving in a two-dimensional space, that in certain conditions exhibit emergent superstructures. Those superstructures are self-organized dynamic networks, resulting from a synchronization process of many units, over length scales much greater than the interaction length. Such networks compartmentalize the twodimensional space with no a priori constraints, due to the formation of porous transport walls, and represent a highly complex and novel non-linear behavior. The analysis is numerically carried out as a function of a control parameter showing distinct regimes: static, stable dynamic networks, intermittency, and chaos. A statistical analysis is drawn to determine the control parameter ranges for the various behaviors to appear. The model and the results shown in this work are expected to contribute to the field of artificial life.
Optical Feedback Regimes Suitable for Distance Measurement with a Ring Laser
2021 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), 2021
We numerically study the behavior of a ring laser subject to bidirectional delayed optical feedba... more We numerically study the behavior of a ring laser subject to bidirectional delayed optical feedback, when the isolated laser is in the quasi-unidirectional regime. We find different regimes, two of which are of special interest, because the laser switching period, between the clockwise and the counter-clockwise mode, is linearly related to the time of flight from the laser to one or both remote reflectors. These regimes are thus suitable to implement a telemeter.
PloS one, 2017
In this work we show how global self-organized patterns can come out of a disordered ensemble of ... more In this work we show how global self-organized patterns can come out of a disordered ensemble of point oscillators, as a result of a deterministic, and not of a random, cooperative process. The resulting system dynamics has many characteristics of classical thermodynamics. To this end, a modified Kuramoto model is introduced, by including Euclidean degrees of freedom and particle polarity. The standard deviation of the frequency distribution is the disorder parameter, diversity, acting as temperature, which is both a source of motion and of disorder. For zero and low diversity, robust static phase-synchronized patterns (crystals) appear, and the problem reverts to a generic dissipative many-body problem. From small to moderate diversity crystals display vibrations followed by structure disintegration in a competition of smaller dynamic patterns, internally synchronized, each of which is capable to manage its internal diversity. In this process a huge variety of self-organized dynami...
We introduce a model for the dynamic self-organization of the electric grid. The model is charact... more We introduce a model for the dynamic self-organization of the electric grid. The model is characterized by a conserved magnitude, energy, that can travel following the links of the network to satisfy nodes' load. The load fluctuates in time causing local overloads that drive the dynamic evolution of the network topology. Our model displays a transition from a fully connected
Technological challenges for CW operation of small-radius semiconductor ring lasers - art. no. 61840R
Proceedings of Spie the International Society For Optical Engineering, Apr 21, 2006
ABSTRACT
Proceedings of Spie the International Society For Optical Engineering, 2008
We have analyzed experimentally and theoretically the modal properties of a semiconductor ring la... more We have analyzed experimentally and theoretically the modal properties of a semiconductor ring laser and the wavelength jumps that occur in connection with directional switching above threshold. A transfer matrix analysis allow us to explain the transfer function measurements when amplified spontaneous emission in the cavity is accounted for. Moreover the transfer matrix analysis permits to determine the threshold condition for the laser modes, which split in two branches due to the symmetry breaking imposed by the output coupler and output waveguides. The wavelength jumps displayed by the device above threshold are interpreted with the frequency splitting and threshold difference between these two branches of solutions, together with the redshift of the material gain.
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Papers by Alessandro Scirè