Now showing items 1-20 of 100

    • About the oscillatory possibilities of the dynamical systems 

      Herrero Simon, Ramon; Pi Vila, Francesc; Rius, J; Orriols Tubella, Gaspar (2009-11)
      External research report
      Open Access
      This paper may be ultimately described as an attempt to make feasible the evolutionary emergence of novelty in a supposedly deterministic world whose behavior is associated with that of the mathematical dynamical systems. ...
    • Acoustically penetrable sonic crystals based on fluid-like scatterers 

      Cebrecos, A.; Romero García, Vicenç; Pico Vila, Rubén; Sánchez Morcillo, Victor José; Botey Cumella, Muriel; Herrero Simon, Ramon; Cheng, Yu Chieh; Staliunas, Kestutis (2015-01-21)
      Article
      Open Access
      We propose a periodic structure that behaves as a fluid-fluid composite for sound waves, where the building blocks are clusters of rigid scatterers. Such building-blocks are penetrable for acoustic waves, and their properties ...
    • All-dielectric self-cloaked structures 

      Hayran, Zeki; Kurt, H.; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (2018-03-17)
      Article
      Open Access
      A general procedure to design objects that are intrinsically invisible (without the necessity of an external cloak) has not been demonstrated so far. Here we propose a flexible method to design such self-cloaked objects ...
    • Asymmetric light transmission by using 2D PT-symmetric photonic nanostructure 

      Turduev, M.; Botey Cumella, Muriel; Herrero Simon, Ramon; Kurt, H.; Staliunas, Kestutis; Giden, I. (Wiley-IEEE Press, 2015)
      Conference report
      Restricted access - publisher's policy
      We propose for the first time a simple realization of a two-dimensional Parity-Time symmetric hexagonal shaped photonic structure composed of honeycomb lattice. The structure has a symmetric periodic modulation of the ...
    • Asymmetric light transmission in PT-Symmetric microring resonators 

      Giden, I.; Dadashi, Kh.; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis; Kurt, Hamza (2016-03-15)
      Article
      Restricted access - publisher's policy
      We propose a new type of add-drop microring resonator made of gain and loss materials. Microring resonators are compact, narrow band, and optical channel dropping filters. In such linear systems, light transmission to ...
    • Asymmetric transmission from a 2D PT-symmetric honeycomb nanostructure 

      Botey Cumella, Muriel; Herrero Simon, Ramon; Turduev, M.; Zhao, D.; Giden, I.; Kurt, H.; Staliunas, Kestutis (Institute of Electrical and Electronics Engineers (IEEE), 2014)
      Conference lecture
      Restricted access - publisher's policy
      We propose a simple realization of a 2-dimensonal (2D) PT-symmetric photonic structure: a honeycomb arrangement of alternating cylinders with gain or loss in a dielectric background. The structure provides a periodic ...
    • Axisymmetric photonic structures with PT-symmetry 

      Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2016)
      Conference report
      Open Access
      PT-symmetric structures in photonic crystals, combining refractive index and gain-loss modulations is becoming a research field with increasing interest due to the light directionality induced by these particular potentials. ...
    • Beam shaping in spatially modulated broad-area semiconductor amplifiers 

      Herrero Simon, Ramon; Botey Cumella, Muriel; Radziunas, Mindaugas; Staliunas, Kestutis (2012-12-15)
      Article
      Open Access
      We propose and analyze a beam-shaping mechanism that in broad-area semiconductor amplifiers occurs due to spatial pump modulation on a micrometer scale. The study, performed under realistic parameters and conditions, ...
    • Brightness enhancement in Non-Hermintian VCSELs 

      Waseem Ahmed, Waqas; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (Optical Society of American (OSA), 2019)
      Conference report
      Restricted access - publisher's policy
      Vertical Cavity Surface Emitting lasers (VCSELs) are compact and efficient light sources useful for a variety of applications. However, due to lack of a transverse mode control mechanism, such lasers suffer from poor spatial ...
    • Chiral modes in 2D PT-symmetric nanostructures 

      Botey Cumella, Muriel; Herrero Simon, Ramon; Turduev, M.; Kurt, H.; Staliunas, Kestutis (Springer International Publishing, 2015-11-15)
      Part of book or chapter of book
      Restricted access - publisher's policy
      We propose the stabilization of the output beam of Broad Area Semiconductor (BAS) amplifiers through the introduction of a spatially periodic modulated potential. We show that a periodic modulation of the pump profile in ...
    • Control and enhancement of beam quality of broadarea semiconductor devices and arrays by multimode interference couplers and two-dimensional gain modulation 

      Murad, M.; Sorel, M.; Herrero Simon, Ramon; Botey Cumella, Muriel; Marsh, J.H.; Staliunas, Kestutis (Institute of Electrical and Electronics Engineers (IEEE), 2013)
      Conference report
      Open Access
      It is proposed to control the beam quality of broad-area semiconductor devices by two-dimensional structuring enforcing phase coherence across the device. First results based on MMI couplers are presented.
    • Designable Dynamical Systems for the Generalized Landau Scenario and the Nonlinear Complexification of Periodic Orbits 

      Herrero Simon, Ramon; Farjas Silva, Jordi; Pi Vila, Francesc; Orriols Tubella, Gaspar (2021-02)
      External research report
      Open Access
      We have found a way for penetrating the space of the dynamical systems towards systems of arbitrary dimension exhibiting the nonlinear mixing of a large number of oscillation modes through which extraordinarily complex ...
    • Diffractive effects in 1D and 2D gain/loss periodic spatial modulated materials 

      Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (IEEE Press. Institute of Electrical and Electronics Engineers, 2010)
      Conference report
      Restricted access - publisher's policy
      The propagation of light through materials with periodically modulated gain can present different effects that are analyzed in the paper. The characterization of these gain/loss metamaterials (GLM) with a two-dimensional ...
    • Directionality fields generated by a local Hilbert transform 

      Ahmed Waseem, Waqas Waseem; Herrero Simon, Ramon; Botey Cumella, Muriel; Hayran, Zeki; Kurt, Hamza; Staliunas, Kestutis (American Physical Society, 2018-03-15)
      Article
      Open Access
      We propose an approach based on a local Hilbert transform to design non-Hermitian potentials generating arbitrary vector fields of directionality, ¿p(¿r), with desired shapes and topologies. We derive a local Hilbert ...
    • Dispersion management in spatially modulated broad band semiconductors 

      Herrero Simon, Ramon; Botey Cumella, Muriel; Khumar, N.P.; Staliunas, Kestutis (IEEE, 2011)
      Conference report
      Restricted access - publisher's policy
    • Enhanced transmission band in periodic media with loss modulation 

      Cebrecos, A.; Pico Vila, Rubén; Romero García, Vicenç; Yasser, A.M.; Maigyte, Lina; Herrero Simon, Ramon; Botey Cumella, Muriel; Sánchez Morcillo, Victor José; Staliunas, Kestutis (2014-11-17)
      Article
      Open Access
      We study the propagation of waves in a periodic array of absorbing layers. We report an anomalous increase of wave transmission through the structure related to a decrease of the absorption around the Bragg frequencies. ...
    • Far-field narrowing in spatially modulated broad-area edge-emitting semiconductor amplifiers 

      Radziunas, Mindaugas; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (2015-05-01)
      Article
      Open Access
      We perform a detailed theoretical analysis of the far-field narrowing in broad-area edge-emitting semiconductor amplifiers that are electrically injected through contacts periodically modulated in both longitudinal and ...
    • Field concentration by Axisymmetric local PT-symmetry 

      Ahmed Waseem, Waqas Waseem; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis (2016)
      Conference report
      Open Access
      We propose a new class of systems holding PT-symmetry only locally; the potential fulfills: U(r-r0)=U*(-r+r0 ) in a small neighborhood of any point r0, whereas on a global scale the system is only Parity symmetric: ...
    • FÍSICA (1r quadrimestre, 2n parcial) 

      Herrero Simon, Ramon (Universitat Politècnica de Catalunya, 2011-01-17)
      Exam
      Restricted access to the UPC academic community
    • FÍSICA (Dinàmica - 1r quadrimestre 1a avaluació) 

      Herrero Simon, Ramon (Universitat Politècnica de Catalunya, 2009-11-03)
      Exam
      Restricted access to the UPC academic community