Articles de revista
http://hdl.handle.net/2117/3271
2016-07-27T23:06:35ZLeaky modes in multilayer uniaxial optical waveguides
http://hdl.handle.net/2117/87738
Leaky modes in multilayer uniaxial optical waveguides
Torner Sabata, Lluís; Canal Bienzobas, Fernando; Hernández Marco, Jordi
The propagation characteristics of the leaky modes in planar anisotropic waveguides with a multilayer structure have been investigated by means of a compact rigorous formalism. The leakage losses and leaky transition angle have been studied for the fundamental and first hybrid modes. An inhomogeneous waveguide and buffered step index type structure have been discussed. Particular attention has been devoted to the variation of the loss coefficient of the leaky modes as a function of buffer thickness and buffer refractive index. A notably different behavior has been obtained for various configurations.
2016-06-06T14:45:48ZTorner Sabata, LluísCanal Bienzobas, FernandoHernández Marco, JordiThe propagation characteristics of the leaky modes in planar anisotropic waveguides with a multilayer structure have been investigated by means of a compact rigorous formalism. The leakage losses and leaky transition angle have been studied for the fundamental and first hybrid modes. An inhomogeneous waveguide and buffered step index type structure have been discussed. Particular attention has been devoted to the variation of the loss coefficient of the leaky modes as a function of buffer thickness and buffer refractive index. A notably different behavior has been obtained for various configurations.Self-homodyne detection of the light orbital angular momentum
http://hdl.handle.net/2117/87170
Self-homodyne detection of the light orbital angular momentum
Belmonte Molina, Aniceto; Pérez Torres, Juan
A simple optical system for the self-homodyne detection of the orbital angular momentum (OAM) carried by optical
beams is introduced. We propose two different schemes based on the use of optical hybrids, which could detect the
OAM mode number, even when the input beam might be slightly distorted. A balanced receiver is used to perform a
self-homodyne measure of the optical signal from two different locations at the beam wavefront.
2016-05-18T15:28:44ZBelmonte Molina, AnicetoPérez Torres, JuanA simple optical system for the self-homodyne detection of the orbital angular momentum (OAM) carried by optical
beams is introduced. We propose two different schemes based on the use of optical hybrids, which could detect the
OAM mode number, even when the input beam might be slightly distorted. A balanced receiver is used to perform a
self-homodyne measure of the optical signal from two different locations at the beam wavefront.Decoupled illumination detection in light sheet microscopy for fast volumetric imaging
http://hdl.handle.net/2117/87133
Decoupled illumination detection in light sheet microscopy for fast volumetric imaging
OLARTE, Omar Eduardo; Andilla, Jordi; Artigas García, David; Loza Álvarez, Pablo
Current microscopy demands the visualization of large threedimensional samples with increased sensitivity, higher resolution, and faster speed. Several imaging techniques based on widefield, point-scanning, and light-sheet strategies have been
designed to tackle some of these demands. Although successful, all these require the illuminated volumes to be tightly coupled with the detection optics to accomplish efficient optical sectioning. Here, we break this paradigm and produce
optical sections from out-of-focus planes. This is done by extending the depth of field of the detection optics in a lightsheet microscope using wavefront-coding techniques. This passive technique allows accommodation of the light sheet
at any place within the extended axial range. We show that this enables quick scanning of the light sheet across a volumetric sample. As a consequence, imaging speeds faster than twice the volumetric video rate (>70 volumes/s) can be
achieved without needing to move the sample. These capabilities are demonstrated for volumetric imaging of fast dynamics in vivo as well as for fast, three-dimensional particle tracking.
2016-05-17T16:58:08ZOLARTE, Omar EduardoAndilla, JordiArtigas García, DavidLoza Álvarez, PabloCurrent microscopy demands the visualization of large threedimensional samples with increased sensitivity, higher resolution, and faster speed. Several imaging techniques based on widefield, point-scanning, and light-sheet strategies have been
designed to tackle some of these demands. Although successful, all these require the illuminated volumes to be tightly coupled with the detection optics to accomplish efficient optical sectioning. Here, we break this paradigm and produce
optical sections from out-of-focus planes. This is done by extending the depth of field of the detection optics in a lightsheet microscope using wavefront-coding techniques. This passive technique allows accommodation of the light sheet
at any place within the extended axial range. We show that this enables quick scanning of the light sheet across a volumetric sample. As a consequence, imaging speeds faster than twice the volumetric video rate (>70 volumes/s) can be
achieved without needing to move the sample. These capabilities are demonstrated for volumetric imaging of fast dynamics in vivo as well as for fast, three-dimensional particle tracking.Leaky modes in multilayer anisotropic optical waveguides
http://hdl.handle.net/2117/86257
Leaky modes in multilayer anisotropic optical waveguides
Torner Sabata, Lluís; Canal Bienzobas, Fernando; Hernández Marco, Jordi
The propagation characteristics of the leaky modes in planar anisotropic waveguides with a multilayer structure have been investigated by means of a compact rigorous formalism. The leakage losses and leaky transition angle have been studied for the fundamental and first hybrid modes. An inhomogeneous waveguide and buffered step index type structure have been discussed. Particular attention has been devoted to the variation of the loss coefficient of the leaky modes as a function of buffer thickness and buffer refractive index. A notably different behavior has been obtained for various configurations.
2016-04-27T13:04:06ZTorner Sabata, LluísCanal Bienzobas, FernandoHernández Marco, JordiThe propagation characteristics of the leaky modes in planar anisotropic waveguides with a multilayer structure have been investigated by means of a compact rigorous formalism. The leakage losses and leaky transition angle have been studied for the fundamental and first hybrid modes. An inhomogeneous waveguide and buffered step index type structure have been discussed. Particular attention has been devoted to the variation of the loss coefficient of the leaky modes as a function of buffer thickness and buffer refractive index. A notably different behavior has been obtained for various configurations.Non reciprocal phase matching in four-layer magnetooptical waveguides
http://hdl.handle.net/2117/86211
Non reciprocal phase matching in four-layer magnetooptical waveguides
Hernández Marco, Jordi; Canal Bienzobas, Fernando; Torner Sabata, Lluís
Non reciprocal single-mode conversion TE0¿TM0 in a four-layer magnetooptical waveguide has been studied as a function of the external applied magnetic field.
2016-04-26T15:27:07ZHernández Marco, JordiCanal Bienzobas, FernandoTorner Sabata, LluísNon reciprocal single-mode conversion TE0¿TM0 in a four-layer magnetooptical waveguide has been studied as a function of the external applied magnetic field.Applicability of the.Lorentzian peak method to analyze leaky and lossy optical waveguides
http://hdl.handle.net/2117/84983
Applicability of the.Lorentzian peak method to analyze leaky and lossy optical waveguides
Torner Sabata, Lluís; Canal Bienzobas, Fernando
Several conclusions concerning the applicability of the Lorentzian peak method to compute the complex propagation constant of leaky and lossy waveguide modes are established.
2016-03-31T13:21:27ZTorner Sabata, LluísCanal Bienzobas, FernandoSeveral conclusions concerning the applicability of the Lorentzian peak method to compute the complex propagation constant of leaky and lossy waveguide modes are established.Suppression and restoration of disorder-induced light localization mediated by PT-symmetry breaking
http://hdl.handle.net/2117/84920
Suppression and restoration of disorder-induced light localization mediated by PT-symmetry breaking
Kartashov, Yaroslav V.; Hang, Chao; Konotop, Vladimir V; Vysloukh, Victor A.; Huang, Guoxiang; Torner Sabata, Lluís
We uncover that the breaking point of the PT-symmetry in optical waveguide arrays has a dramatic impact on light localization induced by the off-diagonal disorder. Specifically, when the gain/loss control parameter approaches a critical value at which PT-symmetry breaking occurs, a fast growth of the coupling between neighboring waveguides causes diffraction to dominate to an extent that light localization is strongly suppressed and the statistically averaged width of the output pattern substantially increases. Beyond the symmetry-breaking point localization is gradually restored, although in this regime the power of localized modes grows upon propagation. The strength of localization monotonically increases with disorder at both broken and unbroken PT-symmetry. Our findings are supported by statistical analysis of parameters of stationary eigenmodes of disordered-symmetric waveguide arrays and by analysis of dynamical evolution of single-site excitations in such structures. Parity-time (PT)- symmetric waveguides feature real spectra despite the presence of gain and losses. A spectrum becomes complex at the symmetry-breaking point as the guide characteristics are changed. This paper reports on disorder-induced localization caused by off-diagonal disorder introduced into a PT-symmetric periodic waveguide array. Localization is suppressed near and restored far beyond the symmetry-breaking point. The phenomenon is explained by enhancement of the diffraction in the symmetry-breaking point.
2016-03-30T18:53:04ZKartashov, Yaroslav V.Hang, ChaoKonotop, Vladimir VVysloukh, Victor A.Huang, GuoxiangTorner Sabata, LluísWe uncover that the breaking point of the PT-symmetry in optical waveguide arrays has a dramatic impact on light localization induced by the off-diagonal disorder. Specifically, when the gain/loss control parameter approaches a critical value at which PT-symmetry breaking occurs, a fast growth of the coupling between neighboring waveguides causes diffraction to dominate to an extent that light localization is strongly suppressed and the statistically averaged width of the output pattern substantially increases. Beyond the symmetry-breaking point localization is gradually restored, although in this regime the power of localized modes grows upon propagation. The strength of localization monotonically increases with disorder at both broken and unbroken PT-symmetry. Our findings are supported by statistical analysis of parameters of stationary eigenmodes of disordered-symmetric waveguide arrays and by analysis of dynamical evolution of single-site excitations in such structures. Parity-time (PT)- symmetric waveguides feature real spectra despite the presence of gain and losses. A spectrum becomes complex at the symmetry-breaking point as the guide characteristics are changed. This paper reports on disorder-induced localization caused by off-diagonal disorder introduced into a PT-symmetric periodic waveguide array. Localization is suppressed near and restored far beyond the symmetry-breaking point. The phenomenon is explained by enhancement of the diffraction in the symmetry-breaking point.Normalized parameters for Y-branch optical waveguides
http://hdl.handle.net/2117/84642
Normalized parameters for Y-branch optical waveguides
Recolons Martos, Jaume; Torner Sabata, Lluís; Canal Bienzobas, Fernando
Y-branch optical waveguides are analyzed in terms of normalized parameters by means of the usual modal analysis. With these parameters the number of variables of the problem is reduced, and universal plots for the mode conversion are obtained. Our results show that the normalized parameters are useful for the design of branching waveguides more tolerant of fabrication errors.
2016-03-17T14:35:14ZRecolons Martos, JaumeTorner Sabata, LluísCanal Bienzobas, FernandoY-branch optical waveguides are analyzed in terms of normalized parameters by means of the usual modal analysis. With these parameters the number of variables of the problem is reduced, and universal plots for the mode conversion are obtained. Our results show that the normalized parameters are useful for the design of branching waveguides more tolerant of fabrication errors.Noise-assisted energy transport in electrical oscillator networks with off-diagonal dynamical disorder
http://hdl.handle.net/2117/84496
Noise-assisted energy transport in electrical oscillator networks with off-diagonal dynamical disorder
De León Montiel, J. Roberto; Quiroz Juarez, Mario A.; Quintero Torres, Rafael; Domínguez Juárez, Jorge Luis; Moya Cessa, Hector M.; Pérez Torres, Juan; ARAGÓN HERNÁNDEZ, JOSÉ LUÍS
Noise is generally thought as detrimental for energy transport in coupled oscillator networks. However, it has been shown that for certain coherently evolving systems, the presence of noise can enhance, somehow unexpectedly, their transport efficiency; a phenomenon called environment-assisted quantum transport (ENAQT) or dephasing-assisted transport. Here, we report on the experimental observation of such effect in a network of coupled electrical oscillators. We demonstrate that by introducing stochastic fluctuations in one of the couplings of the network, a relative enhancement in the energy transport efficiency of 22.5 ± 3.6% can be observed.
2016-03-16T13:49:51ZDe León Montiel, J. RobertoQuiroz Juarez, Mario A.Quintero Torres, RafaelDomínguez Juárez, Jorge LuisMoya Cessa, Hector M.Pérez Torres, JuanARAGÓN HERNÁNDEZ, JOSÉ LUÍSNoise is generally thought as detrimental for energy transport in coupled oscillator networks. However, it has been shown that for certain coherently evolving systems, the presence of noise can enhance, somehow unexpectedly, their transport efficiency; a phenomenon called environment-assisted quantum transport (ENAQT) or dephasing-assisted transport. Here, we report on the experimental observation of such effect in a network of coupled electrical oscillators. We demonstrate that by introducing stochastic fluctuations in one of the couplings of the network, a relative enhancement in the energy transport efficiency of 22.5 ± 3.6% can be observed.Diffraction control in P T -symmetric photonic lattices: from beam rectification to dynamic localization
http://hdl.handle.net/2117/84253
Diffraction control in P T -symmetric photonic lattices: from beam rectification to dynamic localization
Kartashov, Yaroslav V.; Vysloukh, Victor A.; Konotop, Vladimir V; Torner Sabata, Lluís
We address the propagation of light beams in longitudinally modulated PT-symmetric lattices, built as arrays of couplers with periodically varying separation between their channels, and show a number of possibilities for efficient diffraction control available in such nonconservative structures. The dynamics of light in such lattices crucially depends on the ratio of the switching length for the straight segments of each coupler and the longitudinal lattice period. Depending on the longitudinal period, one can achieve either beam rectification when the input light propagates at a fixed angle across the structure without diffractive broadening or dynamic localization when the initial intensity distribution is periodically restored after each longitudinal period. Importantly, the transition between these two different propagation regimes can be achieved by tuning only gain and losses acting in the system, provided that the PT symmetry remains unbroken. The impact of Kerr nonlinearity is also discussed.
2016-03-11T18:26:54ZKartashov, Yaroslav V.Vysloukh, Victor A.Konotop, Vladimir VTorner Sabata, LluísWe address the propagation of light beams in longitudinally modulated PT-symmetric lattices, built as arrays of couplers with periodically varying separation between their channels, and show a number of possibilities for efficient diffraction control available in such nonconservative structures. The dynamics of light in such lattices crucially depends on the ratio of the switching length for the straight segments of each coupler and the longitudinal lattice period. Depending on the longitudinal period, one can achieve either beam rectification when the input light propagates at a fixed angle across the structure without diffractive broadening or dynamic localization when the initial intensity distribution is periodically restored after each longitudinal period. Importantly, the transition between these two different propagation regimes can be achieved by tuning only gain and losses acting in the system, provided that the PT symmetry remains unbroken. The impact of Kerr nonlinearity is also discussed.