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Puebla de Zaragoza, Mexico

Avendano C.G.,Madero University | Reyes J.A.,National Autonomous University of Mexico
Optics Communications | Year: 2010

We consider a nonlinear cylindrical fiber with a nematic liquid crystal (LC) core having initially the escaped configuration and subject to the action of a normal mode propagating electromagnetic field of arbitrary intensity. We derive a set of coupled equations governing the nonlinear dynamics of the electromagnetic field and the confined LC. We solve numerically these coupled equations and find simultaneously the distorted textures of the nematic inside the cylinder and the Transverse Magnetic modes in the guide. We analyze the dependence of these solutions on the electromagnetic field intensity by assuming consistently soft boundary conditions. We have found a dramatic correlation in the spatial distribution of the nematic's configuration and the Transverse Magnetic modes. Thus, the director adopts configurations completely guided by the specific mode involved. We show that the cut-off frequencies and dispersion relations can be tuned by varying the intensity of the electromagnetic propagating field. © 2010 Elsevier B.V. All rights reserved. Source


Salazar-Ramirez M.,National Polytechnic Institute of Mexico | Martinez D.,Madero University | Granados V.D.,National Polytechnic Institute of Mexico | Mota R.D.,National Polytechnic Institute of Mexico
International Journal of Theoretical Physics | Year: 2010

We apply the Schrödinger factorization to construct the generators of the dynamical algebra su(1,1) for the radial equation of the generalized MICZ-Kepler problem. © Springer Science+Business Media, LLC 2010. Source


Avendano C.G.,Madero University | Reyes J.A.,National Autonomous University of Mexico
Optics Communications | Year: 2014

We consider a one-dimensional nonlinear photonic crystal consisting of an infinite set of concentrated equidistant scatterers inserted in a linear dielectric medium. Each of the scatterers is made by a very thin layer of a nonlinear medium with high refractive index that we model by a delta function. We show that the nonlinear optical exact solutions of this system form an intensity dependent band structure. To analyze the stability of these solutions we consider a modulation harmonic perturbation of these solutions whose amplitudes are slightly above the instability threshold. We demonstrate that the nonlinearity gives rise to an oscillatory instability of the solutions, which is a localized version of the well-known modulational instability of the nonlinear Schrodinger equation. We show that the linear harmonic perturbation forms as well a band structure whose allowed bands coincide for some intervals with those of the nonlinear band structure of the solutions for which case the structures are unstable whereas in the region where both the linear and nonlinear bands do not coincide, the nonlinear waves are indeed stable so that they conform spatial solitons. © 2014 Elsevier B.V. Source


Avendano C.G.,Madero University | Reyes J.A.,National Autonomous University of Mexico
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

The multiplet structure of the optical defect modes generated within the bandgap are analyzed by a finite number of identical equispaced twist defects in axially elongated cholesteric elastomers. It is shown that n 0 defect modes induced by n 0 twist defects can be mechanically tuned. The transfer matrix is obtained and the defect frequencies when n 0=1,2 are expressed in terms of twist angle, fractional shape anisotropy, and longitudinal deformation. For n 0=2, the coupling between modes is analytically studied and it is shown that when the separation between defects is much larger than the line width, the defect modes do not interact and become degenerated. © 2012 American Physical Society. Source


Sevilla F.J.,National Autonomous University of Mexico | Olivares-Quiroz L.,Madero University
European Journal of Physics | Year: 2012

In this work, we address the concept of the chemical potential μ in classical and quantum gases towards the calculation of the equation of state μ = μ(n, T) where n is the particle density and T the absolute temperature using the methods of equilibrium statistical mechanics. Two cases seldom discussed in elementary textbooks are presented with detailed calculations. The first one refers to the explicit calculation of μ for the interacting classical gas exemplified by van der Waals gas. For this purpose, we used the method described by van Kampen (1961 Physica 27 783). The second one refers to the calculation of μ for ideal quantum gases that obey a generalized Pauli's exclusion principle that leads to statistics that go beyond the BoseEinstein and FermiDirac cases. The audience targeted in this work corresponds mainly to advanced undergraduates and graduate students in the physicalchemical sciences but it is not restricted to them. In regard of this, we have put a special emphasis on showing some additional details of calculations that usually do not appear explicitly in textbooks. © 2012 IOP Publishing Ltd. Source

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