Concepción, Chile
Concepción, Chile

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Naether U.,University of Chile | Naether U.,Center for Optics and Photonics | Naether U.,Friedrich - Schiller University of Jena | Kartashov Y.V.,Polytechnic University of Catalonia | And 6 more authors.
Optics Letters | Year: 2012

We study the gradual transition from one-dimensional (1D) to two-dimensional (2D) Anderson localization upon transformation of the dimensionality of disordered waveguide arrays. An effective transition from a 1D to a 2D system is achieved by increasing the number of rows forming the arrays. We observe that, for a given disorder level, Anderson localization becomes weaker with increasing numbers of rows-hence the effective dimension. © 2012 Optical Society of America.


Rojas-Rojas S.,University of Chile | Rojas-Rojas S.,Center for Optics and Photonics | Vicencio R.A.,University of Chile | Vicencio R.A.,Center for Optics and Photonics | And 4 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Modulational instability and discrete matter wave solitons in dipolar BECs, loaded into a deep optical lattice, are investigated analytically and numerically. The process of modulational instability of nonlinear plane matter waves in a dipolar nonlinear lattice is studied and the regions of instability are established. The existence and stability of bulk discrete solitons are analyzed analytically and confirmed by numerical simulations. In marked contrast with the usual discrete nonlinear Schrödinger behavior (no dipolar interactions), we found a region where the two fundamental modes are simultaneously unstable, allowing enhanced mobility across the lattice for large norm values. To study the existence and properties of surface discrete solitons, an analysis of the dimer configuration is performed. The properties of symmetric and antisymmetric modes including stability diagrams and bifurcations are investigated in closed form. For the case of a bulk medium, properties of fundamental on-site and intersite localized modes are analyzed. On-site and intersite surface localized modes are studied, and we find that they do not exist when nonlocal interactions predominate with respect to local ones. © 2011 American Physical Society.


Molina M.I.,University of Chile | Miroshnichenko A.E.,Center for Optics and Photonics | Miroshnichenko A.E.,Australian National University | Kivshar Y.S.,Center for Optics and Photonics
Physical Review Letters | Year: 2012

We introduce a novel concept of surface bound states in the continuum, i.e., surface modes embedded into the linear spectral band of a discrete lattice. We suggest an efficient method for creating such surface modes and the local bounded potential necessary to support the embedded modes. We demonstrate that the surface embedded modes are structurally stable, and the position of their eigenvalues inside the spectral band can be tuned continuously by adding weak nonlinearity. © 2012 American Physical Society.


Naether U.,University of Chile | Naether U.,Center for Optics and Photonics | Naether U.,Friedrich - Schiller University of Jena | Meyer J.M.,Friedrich - Schiller University of Jena | And 6 more authors.
Optics Letters | Year: 2012

We investigate experimentally the light evolution inside a two-dimensional finite periodic array of weakly coupled optical waveguides with a disordered boundary. For a completely localized initial condition away from the surface, we find that the disordered boundary induces an asymptotic localization in the bulk, centered around the initial position of the input beam. © 2012 Optical Society of America.


Molina M.I.,University of Chile | Molina M.I.,Center for Optics and Photonics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We consider a simplified model for a nonlinear magnetic metamaterial, consisting of a split-ring resonator (SRR) array capable of nonlinear capacitive response. We compute the localized modes around simple magnetoinductive impurities located at the bulk of the array, in closed form for both, linear and nonlinear cases. We also examine the scattering of magnetoinductive waves across internal (external) capacitive (inductive) defects coupled to the SRR array, and examine the ocurrence of Fano resonances, and how to tune them by changing the external parameters of the system. Finally, we describe a method for building a stable localized magnetoinductive mode embedded in the continous band of extended states. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).


Naether U.,University of Chile | Naether U.,Center for Optics and Photonics | Molina M.I.,University of Chile | Molina M.I.,Center for Optics and Photonics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We study the scattering of magnetoinductive plane waves by internal (external) capacitive (inductive) defects coupled to a one-dimensional split-ring resonator array. We examine a number of simple defect configurations where Fano resonances occur and study the behavior of the transmission coefficient as a function of the controllable external parameters. We find that for embedded capacitive defects, the addition of a small amount of coupling to second neighbors is necessary for the occurrence of Fano resonance. For external inductive defects, Fano resonances are commonplace, and they can be tuned by changing the relative orientation or distance between the defect and the SSR array. © 2011 American Physical Society.


Martinez A.J.,University of Chile | Molina M.I.,Center for Optics and Photonics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study discrete surface solitons in semi-infinite, one-dimensional, nonlinear (Kerr), quasiperiodic waveguide arrays of the Fibonacci and Aubry-André types, and explore different families of localized surface modes, as a function of optical power content ("nonlinearity") and quasiperiodic strength ("disorder"). We find a strong asymmetry in the power content of the mode as a function of the propagation constant, between the cases of focusing and defocusing nonlinearity, in both models. We also examine the dynamical evolution of a completely localized initial excitation at the array surface. We find that, in general, for a given optical power, a smaller quasiperiodic strength is required to effect localization at the surface than in the bulk. Also, for fixed quasiperiodic strength, a smaller optical power is needed to localize the excitation at the edge than inside the bulk. © 2012 American Physical Society.


Molina M.I.,University of Chile | Molina M.I.,Center for Optics and Photonics | Lazarides N.,University of Crete | Lazarides N.,Foundation for Research and Technology Hellas | And 2 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

We investigate numerically the effect of the competition of disorder, nonlinearity, and boundaries on the Anderson localization of light waves in finite-size, one-dimensional waveguide arrays. Using the discrete Anderson-nonlinear Schrödinger equation, the propagation of the mode amplitudes up to some finite distance is monitored. The analysis is based on the calculated localization length and the participation number, two standard measures for the statistical description of Anderson localization. For relatively weak disorder and nonlinearity, a higher disorder strength is required to achieve the same degree of localization at the edge than in the interior of the array, in agreement with recent experimental observations in the linear regime. However, for relatively strong disorder and/or nonlinearity, this behavior is reversed and it is now easier to localize an excitation at the edge than in the interior. © 2012 American Physical Society.


Bennet F.H.,Australian National University | Molina M.I.,University of Chile | Molina M.I.,Center for Optics and Photonics
Journal of the Optical Society of America B: Optical Physics | Year: 2012

We examine localized surface modes in the core of a photonic crystal fiber composed of a finite nonlinear (Kerr) hexagonal waveguide array containing a topological defect in the form of a central void. Using the coupled-modes approach, we find the fundamental surface mode and the staggered and unstaggered ring-shaped modes, and their linear stability windows, for two void diameters. We find that, for a small void diameter, the unstable unstaggered ring mode of the system always requires less power and its instability gain at low powers is smaller than in the case without the void. Also, for the small void case, the unstaggered ring mode does not require a minimum power threshold, in sharp contrast with the case without the void. For a larger void, most of these observations hold, as well. We follow numerically the dynamical evolution of these ring modes to reveal their decay channels at long propagation distances. © 2012 Optical Society of America.


Mejia-Cortes C.,University of Chile | Mejia-Cortes C.,University of the Atlantic | Mejia-Cortes C.,Center for Optics and Photonics | Molina M.I.,University of Chile
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

We study a one-dimensional binary optical lattice in the presence of diagonal disorder and alternating gain and loss, and examine the light transport phenomena for localized and extended input beams. In the pure PT-symmetric case, we derive an exact expression for the behavior of light localization in terms of typical parameters of the system. Within the PT-symmetric region light localization becomes constant as a function of the strength of the gain and loss parameter, but outside the PT-symmetric window, light localization increases as the gain and loss parameter increases. When disorder is added, we observe that the presence of gain and loss inhibits (favors) the transport for localized (extended) excitations. © 2015 American Physical Society.

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