Now showing items 21-40 of 51

  • Invisibility on demand based on a generalized Hilbert transform 

    Hayran, Zeki; Herrero Simon, Ramon; Botey Cumella, Muriel; Kurt, Hamza; Staliunas, Kestutis (American Physical Society (APS), 2018-07-12)
    Article
    Open Access
    We propose a feasible invisibility approach to suppress the scattering of waves from or to given directions and for particular frequencies, i.e., invisibility on demand. We derive a generalized Hilbert transform for a ...
  • Light in materials with periodic gain-loss modulation on a wavelength scale 

    Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis (2010-07-22)
    Article
    Restricted access - publisher's policy
  • Locally parity-time-symmetric and globally parity-symmetric systems 

    Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (2016-11-11)
    Article
    Open Access
    We introduce a class of systems holding parity-time (PT) symmetry locally, whereas being globally P symmetric. The potential, U = U(vertical bar r vertical bar), fulfills PT symmetry with respect to periodically distributed ...
  • Management of Light Patterns Based on Local Hilbert Transform 

    Staliunas, Kestutis; Ahmed, W.; Botey Cumella, Muriel; Herrero Simon, Ramon; Hayran, Zeki; Kurt, H. (2018)
    Conference report
    Restricted access - publisher's policy
    We propose a new approach of optical field management based on a local Hilbert transform, where the non-Hermitian potentials generating arbitrary vector fields of directionality p(\vec r), with desired shapes and topologies ...
  • Managing spatial diffraction through a periodic loss modulation 

    Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Herrero Simon, Ramon; Maigyte, Lina; Staliunas, Kestutis (2014)
    Conference lecture
    Open Access
    We show that periodic distributions of gain or losses on the wavelength scale allow managing spatial diffraction of light beams, with no index contrast. It has been recently predicted that such artificial periodic structures, ...
  • Negative diffraction by a periodically modulated loss 

    Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Herrero Simon, Ramon; Maigyte, Lina; Picó, Ruben; Staliunas, Kestutis (Institute of Electrical and Electronics Engineers (IEEE), 2013)
    Conference lecture
    Restricted access - publisher's policy
  • Nondiffractive-nondiffusive beams in complex crystals 

    Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (2014-06-16)
    Article
    Open Access
    The study of spatial dispersion of two-dimensional complex crystals, with periodic modulations of both gain-loss and the refractive index, reveals simultaneous nondiffractive-nondiffusive light propagation. Narrow light ...
  • Nonlinear Light Generation at the High Energy Range of a 3D Opal Film 

    Martorell Pena, Jordi; Botey Cumella, Muriel; Maymó Camós, Marc; Molinos-Gómez, Alberto; Dorado, Luís A.; Depine, Ricardo A.; Lozano, Gabriel; Mihi, Agustín; Míguez, Hernán (2009)
    Conference report
    Open Access
  • Una nova experiència docent: cursos voluntaris de preparació als estudis de grau en enginyeria 

    Alcaraz Sendra, Olga; Botey Cumella, Muriel (Universitat Politècnica de Catalunya. Institut de Ciències de l'Educació, 2012-07-06)
    Conference lecture / Conference report
    Open Access
    Descrivim una nova experiència iniciada a l'EUETIB el setembre de 2010: un curs de física de preparació als estudis de grau en enginyeria. En descrivim la organització, el finançament, funcionament i resultats. Constatem ...
  • Numerical and experimental demonstration of a wavelength demultiplexer design by point-defect cavity coupled to a tapered photonic crystal waveguide 

    Hayran, Zeki; Turduev, Mirbek; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis; Kurt, Hamza (2016-01-01)
    Article
    Open Access
    We propose and experimentally demonstrate a demultiplexer with point-defect resonators and a reflection feedback mechanism in a photonic crystal waveguide (PCW). A tapered PCW has been chosen as the necessary reflector, ...
  • Polarization-independent broadband bidirectional optical cloaking using a new type of inverse scattering approach 

    Hayran, Zeki; Herrero Simon, Ramon; Botey Cumella, Muriel; Kurt, Hamza; Staliunas, Kestutis (Institute of Electrical and Electronics Engineers (IEEE), 2017)
    Conference report
    Open Access
    Since the advent of transformation optics a decade ago [1], the ability to achieve optical cloaking has become a matter of practical realization. However, so far extreme material requirements and large device areas have ...
  • PT-axisymmetric photonic nanostructures 

    Ahmed Waseem, Waqas Waseem; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis (2016)
    Conference report
    Restricted access - publisher's policy
    Optical Parity-Time (PT-) symmetric systems support unusual properties. When the symmetric coupling between internal modes is broken the system becomes strongly unidirectional resulting in novel effects such as asymmetric ...
  • PT-axisymmetric VCSELs with linear central defect 

    Ahmed Waseem, Waqas Waseem; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis (Institute of Electrical and Electronics Engineers (IEEE), 2017)
    Conference report
    Open Access
    Semiconductor Lasers and particularly Vertical-Cavity Surface-Emitting Lasers (VCSELs) are important laser sources used for many purposes. However, the applications of these lasers are mainly restricted by their strongly ...
  • PT-axisymmetry for extraordinary field confinement 

    Botey Cumella, Muriel; Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Staliunas, Kestutis (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2017)
    Conference report
    Open Access
    Optical Parity-Time (PT-) symmetric systems support unusual properties when the symmetric coupling between internal modes is broken. We propose a new class of quasiperiodic PT-axisymmetric systems which lead to a simultaneous ...
  • Regularization of vertical-cavity surface-emitting laser emission by periodic non-Hermitian potentials 

    Ahmed, Waqas Waseem; Herrero Simon, Ramon; Botey Cumella, Muriel; Wu, Ying; Staliunas, Kestutis (2019-08-15)
    Article
    Restricted access - publisher's policy
    We propose a novel physical mechanism based on periodicnon-Hermitian potentials to efficiently control the complexspatial dynamics of broad-area lasers, particularly in vertical-cavity surface-emitting lasers (VCSELs), ...
  • Self-collimated beams in 2D complex periodic lattices from P- to PT-symmetry 

    Ahmed Waseem, Waqas Waseem; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis (2017)
    Conference report
    Open Access
    We analyze self-collimation in two-dimensional periodic complex lattices. We consider P-symmetric and PT-symmetric complex lattices with different geometries, where the periodic modulations of both refractive index and ...
  • Self-collimation in 2D Complex P- and PT-symmetric systems 

    Botey Cumella, Muriel; Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Staliunas, Kestutis (2017)
    Conference report
    Open Access
    We predict the self-collimation phenomena (or equivalently, dynamical localization) in 2-dimensional P-symmetric and PT-symmetric complex potentials, with periodic modulations of both gain/loss and refractive index. ...
  • Self-collimation in PT -symmetric crystals 

    Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (AMER PHYSICAL SOC, 2017-05-10)
    Article
    Open Access
    We predict the self-collimation phenomena (or equivalently, dynamical localization) in two-dimensional PT-symmetric complex potentials, where the complex modulation is considered in the transverse, longitudinal, or ...
  • Simulations and analysis of beam quality improvement in spatially modulated broad area edge-emitting devices 

    Radziunas, Mindaugas; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2014)
    Conference report
    Restricted access - publisher's policy
    We simulate and analyze how beam quality improves while being amplified in edge emitting broad area semiconductor amplifiers with a periodic structuring of the electrical contacts, in both longitudinal and lateral directions. ...
  • Slow light enabled wavelength demultiplexing 

    Hayran, Zeki; Turduev, M.; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis; Kurt, H. (Institute of Electrical and Electronics Engineers (IEEE), 2016)
    Conference report
    Open Access
    Photonic crystal waveguides supporting band gap guided modes hold great potential to tailor the group velocity of propagating light. We propose and explore different wavelength demultiplexer design approaches that ...