Publications

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    ABSTRACT: An algorithm to compute the Lyapunov exponents of piecewise linear function-based multidirectional multiscroll chaotic oscillators is reported. Based on the m regions in the piecewise linear functions, the suggested algorithm determines the individual expansion rate of Lyapunov exponents from m-piecewise linear variational equations and their associated m-Jacobian matrices whose entries remain constant during all computation cycles. Additionally, by considering OpAmp-based chaotic oscillators, we study the impact of two analog design procedures on the magnitude of Lyapunov exponents. We focus on analyzing variations of both frequency bandwidth and voltage/current dynamic range of the chaotic signals at electronic system level. As a function of the design parameters, a renormalization factor is proposed to estimate correctly the Lyapunov spectrum. Numerical simulation results in a double-scroll type chaotic oscillator and complex chaotic oscillators generating multidirectional multiscroll chaotic attractors on phase space confirm the usefulness of the reported algorithm.
    Abstract and Applied Analysis 12/2013; 2013:1-11. · 1.10 Impact Factor
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    ABSTRACT: We report the experimental setup of a high power pulsed erbium-doped fiber amplifier. An optical signal at 1550 nm emitted by a distributed feedback laser is amplified by two identical stages in reflective configuration using one fiber Bragg grating at each one of those. We demonstrated that for pulses with a frequency of 20 kHz and temporal duration of 10, 50, 100, and 500 ns, it is possible to obtain output peak powers of 41, 22, 18, and 11 W, respectively. We applied our high power amplifier in the characterization of nonlinear optical transmission of single-wall carbon nanotubes deposited on single mode optical fibers end-face by the photodeposition technique. Our results show that the high power system is ideal for carrying out studies of nonlinear effects in optical fibers as well as nonlinear characterization of nanostructured materials deposited on optical fibers.
    Optics & Laser Technology 11/2013; 52:15-20. · 1.37 Impact Factor
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    ABSTRACT: A trade-off analysis on the chaotic regime in a multi-scroll chaotic system and the uncertainties of its parameters is presented. The chaotic oscillator is modeled by using the state-variables approximation and its nonlinear function is represented as a piecewise linear (PWL) function. In particular, a 4-scroll chaotic system with four parameters is studied. Due to the chaotic behavior depends on the system parameters; linear and random sweeps are performed to obtain an interval for each parameter. This trust interval is used to predict the number of scrolls that can be synthesized under uncertainties and also, the implementation with an electronic circuit based on operational amplifiers. MATLAB simulations confirm the usefulness of the proposed approach.
    Power, Electronics and Computing (ROPEC), 2013 IEEE International Autumn Meeting on; 01/2013
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    ABSTRACT: In this chapter, the guidelines to synchronize one-directional (1D) and two-directional (2D) multi-scroll chaos generators by means of Generalized Hamiltonian forms are presented. First, the multi-scroll chaotic oscillator is simulated at the electronic system level by applying state-variables and piecewise-linear approaches. Besides, we apply scaling procedures to modify the breaking points, slopes and frequency of the chaotic signals in order to reduce their excursion levels within practical values for electronic devices. Second, a chaotic synchronization scheme for multi-directional multi-scroll chaos generators is introduced. We use Generalized Hamiltonian forms approach to determine the synchronization conditions when one and two state-variables of the master system are sent to control the nonlinear functions in the slave system. Additionally, two schemes are set-up to transmit encrypted binary and analog signals by applying chaotic switching technique and additive chaotic masking, respectively. Both schemes are implemented by using traditional operational amplifiers. Finally, theoretical results are confirmed by performing numerical and SPICE simulation results.
    SELECTED TOPICS IN NONLINEAR DYNAMICS AND THEORETICAL ELECTRICAL ENGINEERING, 01/2013: chapter On the synchronization of 1D and 2D multi-scroll chaotic oscillators: pages 19-40; Springer., ISBN: 978-3-642-34560-9
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    ABSTRACT: We study the synchronization of a piecewise linear function-based chaotic system. That system generates multiple scrolls in multiple directions (two- and three-directions) on phase space. In this scenario, the design of a controller based on Generalized Hamiltonian forms is possible. As function of control signals, we propose a master–slave synchronization scheme using 2 n −1 combinations to drive a nonlinear state observer. Associated with this, the piecewise linear functions of the slave are directly controlled by the state-variables of the master system. We computed the synchronization error for each combinations. Besides, the circuit synthesis based on operational amplifiers validates our synchronization scheme by means of SPICE simulations. We observed that the synchronization error at circuit level depends on the number of the control signals used. Our numerical and SPICE simulation results are in agreement showing the usefulness of the proposed approach.
    Nonlinear Dynamics 10/2012; 70(2):1633-1643. · 3.01 Impact Factor
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    ABSTRACT: In this paper, we report the experimental study of synchronous nanosecond pulse generation in an array of three coupled erbium-doped ring fiber lasers. We obtain the pulse generation by means of an amplitude modulator placed in one of the cavities and through the nonlinear energy interaction between the modulated cavity and the other cavities. Synchronous pulse generation is achieved in the array by an appropriate selection of coupling ratio between the cavities and the matching of cavity lengths, as well as the frequency modulation. We confirm synchronous generation through the phase diagrams and the spectral emission.
    IEEE Photonics Journal 01/2012; 4(3):671-678. · 2.36 Impact Factor
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    ABSTRACT: Based on the numerical experiment techniques, we addressed this work to the study of the physical parameters, which allow the discrete soliton formation and propagation in two dimensional waveguide arrays of different geometries. The mathematical model is based on the two dimensional nonlinear Schrödinger equation, and from the boundary conditions we are able to conclude that the array geometry plays an important role in the energy demands for the discrete soliton formation and propagation over distances of hundreds of diffraction lengths. Furthermore, our results are consistent even in the case when we take into account coupling of higher orders.
    Proc SPIE 08/2011;
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    ABSTRACT: The multiple functions and potential applications of nanotechnology have become a necessary and powerful tool in scientific work everyday. Nanotechnology is interdisciplinary science involving physics, chemistry, biology, materials science and wide range of engineering disciplines. His versatility has led to an increasing use in wide range of fields. For example, electronic engineering has shown an interest growing in the design of nanodevices due to continued miniaturization of them. The investigations have focused on the manufacture of electronic circuits and their applications complex systems, in addition to this, nanotechnology already plays an important role in development of new materials with tailored features and chemical properties, so their study is important today. Nanosensors have been under investigation for some institutions in recent years. A nanosensor is a device built on an atomic scale based on measurements nanometers, whose purpose is mainly to obtain data on the atomic scale transfer so they can be easily analyzed. In this work We study wave propagation in a low-dimensional planar nano-waveguide, to establish the principle of operation of an optical structure to propose the design of a nanosensor.
    Proc SPIE 08/2011;
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    ABSTRACT: In this paper, a chaotic synchronization scheme for multi-directional multi-scroll chaos generators is presented. We use Generalized Hamiltonian forms approach to determine the synchronization conditions for two unidirectionally coupled multi-directional multi-scroll chaotic attractors. First, two state variables of the master system are used to control the two nonlinear functions in the slave system and consequently, reach the synchronization of two 2D-4-scroll chaotic systems. Similarly, the synchronization of two 3D-4-scroll chaotic systems is achieved by using all three state-variables in order to control the three nonlinear functions for the slave system. Finally, theoretical calculations are in good agreement with numerical simulations and a prediction on the values for observer gain is also given.
    07/2011;
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    ABSTRACT: In this work we present a theoretical and computational analysis of propagation of low dimensional optical waves using symbolic computational support (MAPLE). We also laid the foundations for late studies for more complex structures.
    IEEE/LEOS Summer Topical Meetings, 2008 Digest of the; 08/2008
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    ABSTRACT: We report the experimental study of a multicavity fiber laser system conformed by an array of three Erbiumdoped fiber laser cavities. We have demonstrated that through the nonlinear interaction of evanescent fields among one cavity with active modulation and all the others it is possible to accomplish the mode‐locking for all the laser cavities. Moreover, the synchronous pulse generation between cavities is obtained with an appropriate selection of pump intensity, frequency modulation and coupling ratio.
    AIP Conference Proceedings. 04/2008; 992(1):435-438.
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    ABSTRACT: In this work, applying the numerical experiment techniques, we demonstrate the stable propagation of (2+1)D spatial solitons, as well as vortex solitons with spin 1 and 2 in a cubic-quadratic nonlinear optical tandem.
    09/2007;
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    ABSTRACT: The optical properties of the nonlinear effective susceptibility of a layered Kerr-Quadratic composite, and the conditions when it is possible to observe cooperative effects of both materials on the nonlinear beam propagation are determined.
    09/2007;
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    E. J. Gualda, L. C. Gómez-Pavón, J. P. Torres
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    ABSTRACT: This paper presents a scheme to enhance the performance of an ultrahigh capacity (100?Gb/s) long haul transmission system that makes use of chirped fibre Bragg gratings (FBG) for dispersion slope compensation. It is shown that the FBG effectively compensate the dispersion slope while at the same time providing appropriate in-line filtering. The penalty to the system performance due to unwanted group delay ripple is also discussed.
    Journal of Modern Optics 01/2005; 52:1197-1206. · 1.16 Impact Factor
  • A. Luis-Ramos, E. Marti-Panameno, L. C. Gomez-Pavon
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    ABSTRACT: Dispersion curves of the modes TE y TM of a two concentric core optical fiber are presented. This fiber, in contrast to multi clad-one, has a layer where it is assumed that guided modes exist. The main characteristic of such a curves is that they are discontinuous.
    Proc SPIE 10/2004; 5622:1193.
  • L.C Gómez-Pavón, E Martı́-Panameño
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    ABSTRACT: Based on the numerical experiment techniques, we report the synchronous pulse generation in multichannel fiber laser systems. The laser arrays under study are conformed by two up to seven nonlinearly coupled doped fibers, separately pumped. Due to the nonlinear interaction between evanescent waves of the active modulated radiation in one of the fibers and the radiation in all other ones, the system achieves the time synchronization – in all channels – of the pulse generation. The characterization of these systems as well as the effect of symmetry breaking on the pulse characteristics are carried out.
    Optics Communications 05/2001; 19(3-6):323-332. · 1.44 Impact Factor
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    ABSTRACT: With the help of numerical experiments we demonstrate the self-starting soliton generation in a dual-core ring fiber laser without any external mode-locking mechanism. This result makes evident that the nonlinear energy switching between the active and the passive cores acts as a self-mode-locking mechanism.
    Optics Communications 01/2001; 194:409-414. · 1.44 Impact Factor
  • L. C. Gómez-Pavón, E. Martí-Panameño
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    ABSTRACT: In this paper, we report the numerical study of the synchronous soliton-like pulses generation in a multichannel fiber laser system, conformed by an array of 2 up to 7 coupled Erbium doped fibers, separately pumped. The pulse synchronous generation is obtained by means of an amplitude modulator inserted in one of the channels, and the energy interaction of evanescent waves between this channel and all the others.
    Proc SPIE 06/2000; 4:878.
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    ABSTRACT: Cadmium sulphide polycrystalline thin films were prepared by chemical-bath deposition (CBD) method onto glass substrates at 80°C. The modification to the traditional technique consists in applying a pulsed electric (E) external fields during the growth process. E was applied in two different orientations with respect to substrate plane surface (SPS): (a)parallel and (b)perpendicular. The as-deposited samples are hard and look yellowish with a shine and smooth surface. In both cases, X-ray diffractograms show slight differences in the crystalline structure, but optical reflection measurements reveal strong anisotropic characteristics, specially in case (b). Atomic force microscopy pictures evidence a large amount of valleys among crystalline grains. This is a resultant effect of the field action.
    Journal of Crystal Growth 01/1998; 187(3):380-386. · 1.55 Impact Factor
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    ABSTRACT: This work presents a basic optomechatronic system development for both third harmonic generation and the characterization of such optical nonlinearities in biological samples. The source for nonlinear optical effects generation is an erbium doped fiber laser with a power of 112 mW, approximately. The control system as well as the acquisition and processing data software were developed in the programming language LabView. The results demonstrated that it was possible to detect the third harmonic generation from samples of rat blood smears.

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