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  • Shaping of linght beams with photonic crystals: spatial filtering, beam collimation and focusing

     Maigyte, Lina
    Defense's date: 2014-07-01
    Department of Physics and Nuclear Engineering, Universitat Politècnica de Catalunya
    Theses

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    La recerca desenvolupada en el marc d'aquesta tesi doctoral és un estudi teòric, numèric i experimental de la modificació de la forma de feixos de llum (filtratge espacial, col·limació i focalització) en el rang visible de freqüències utilitzant estructures de cristall fotònic. Els cristalls fotònics (CFs) són materials amb una modulació periòdica de l'índex de refracció en l'escala de la longitud d'ona, i són principalment coneguts per les seves propietats relacionades amb la dispersió temporal. Tot i això, la dispersió espacial també pot ser modificada mitjançant CFs, fet que permet controlar les propietats espacials de feixos monocromàtics de llum.En la primera part de la tesi, mostrem experimentalment el fet que certes modificacions de la dispersió espacial en CFs poden donar lloc a filtratge espacial (angular) de feixos de llum. L'estudi es focalitza en la millora de l'eficiència del filtratge espacial mitjançant la introducció de "chirp" (la variació del període longitudinal de l'estructura) en el CF. A més, per tal d'incrementar l'efecte considerem diferents estructures i materials. El treball presentat en aquesta tesi doctoral acosta a la realitat la creació d'una nova generació de filtres espacials per a circuits micro-fotònics i micro-dispositius.La segona part d'aquest estudi se centra en l'anàlisi teòric, numèric i experimental de la formació de dispersió espacial negativa en CFs, la gual dóna lloc a efectes de col·limació i focalització un cop travessat el CF. Les idees desenvolupades en aquesta tesi doctoral també són aplicables a sistemes amb pèrdues, en particular a CFs metàl·lics. Els resultats de les simulacions mostren l'existència d'ambdós efectes, filtratge espacial i focalització, en CFs metàl·lics.

  • Beam shaping in two-dimensional metallic photonic crystals photonic crystals

     Pradeep Kumar, Nikhil; Maigyte, Lina; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis
    Journal of the Optical Society of America B. Optical physics
    Date of publication: 2014-03-05
    Journal article

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    We study light beam propagation in periodic metallic nanostructures¿metallic photonic crystals (MPhCs). In particular, we consider a two-dimensional rhombic array of metallic cylinders embedded in air and explore its ability to tailor spatial propagation of light beams. We show that the structure supports self-collimated propagation and negative (anomalous) diffraction. In this later case, flat lensing is observed, leading to the focusing of beams behind the MPhCs. Moreover, the anisotropic attenuation of light provided by the structure enables spatial filtering of noisy beams.

  • Spatial filtering by axisymmetric photonic microstructures

     Purlys, Vytautas; Maigyte, Lina; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Gadonas, Roaldas; Staliunas, Kestutis
    Optics letters
    Date of publication: 2014-02-15
    Journal article

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    We propose and show experimentally axisymmetric spatial (angular) filtering of two-dimensional light beams by axisymmetric photonic microstructures. Such three-dimensional microstructures (similar to photonic crystals), in gapless configuration, were recorded in bulk of glass, where the refractive index has been point-by-point modulated using tightly focused femtosecond laser pulses. Axisymmetric angular filtering of approximately 25 mrad is demonstrated experimentally. (C) 2014 Optical Society of America

  • Enhancement of sound inchirped sonic crystals

     Romero García, Vicenç; Pico Vila, Rubén; Cebrecos Ruiz, Alejandro; Sánchez Morcillo, Victor José; Staliunas, Kestutis
    Applied physics letters
    Date of publication: 2013-03-04
    Journal article

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    We propose and experimentally demonstrate a mechanism of sound wave concentration based on soft reflections in chirped sonic crystals. The reported controlled field enhancement occurs at around particular (bright) planes in the crystal and is related to a progressive slowing down of the sound wave as it propagates along the material. At these bright planes, a substantial concentration of the energy (with a local increase up to 20 times) was obtained for a linear chirp and for frequencies around the first band gap. A simple couple mode theory is proposed that interprets and estimates the observed effects. Wave concentration energy can be applied to increase the efficiency of detectors and absorbers.

  • Phase-bistable Kerr cavity solitons and patterns

     de Valcarcel Gonzalvo, German Jose; Staliunas, Kestutis
    Physical review A
    Date of publication: 2013-04-03
    Journal article

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    We study pattern formation in a passive nonlinear optical cavity on the basis of the classic Lugiato-Lefever model with a periodically modulated injection. When the injection amplitude sign alternates, e.g., following a sinusoidal modulation in time or in space, a phase-bistable response emerges, which is at the root of the spatial pattern formation in the system.

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    Flat lensing by periodic loss-modulated materials  Open access

     Pradeep Kumar, Nikhil; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis
    Journal of the Optical Society of America B. Optical physics
    Date of publication: 2013-09-23
    Journal article

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    We propose a flat lensing effect using a periodic loss-modulated material. In particular, we consider a two-dimensional square and rhombic arrangement of lossy cylinders embedded in a host media with the same refractive index. The effect is predicted by the dispersion curves obtained by a coupled mode expansion of Maxwell equations and by numerical beam propagation experiments. From both analytical and numerical studies, we show that, for a range of frequencies, light beams undergo negative diffraction on propagation through the loss-modulated medium, providing a window of high transmission. The phase shifts accumulated by negative diffraction within the structure are then compensated by normal diffraction, leading to substantial focalization beyond it.

    We propose a flat lensing effect using a periodic loss-modulated material. In particular, we consider a two-dimensional square and rhombic arrangement of lossy cylinders embedded in a host media with the same refractive index. The effect is predicted by the dispersion curves obtained by a coupled mode expansion of Maxwell equations and by numerical beam propagation experiments. From both analytical and numerical studies, we show that, for a range of frequencies, light beams undergo negative diffraction on propagation through the loss-modulated medium, providing a window of high transmission. The phase shifts accumulated by negative diffraction within the structure are then compensated by normal diffraction, leading to substantial focalization beyond it.

    Missatge de l'editor: This paper was published in Journal of the Optical Society of America B and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/josab/abstract.cfm?uri=josab-30-10-2684. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

  • Resonators with intracavity photonic crystals

     Peckus, Martynas; Rogalskis, R; Sirutkaitis, Valdas; Staliunas, Kestutis
    Lithuanian journal of physics
    Date of publication: 2013
    Journal article

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  • Evidences of spatial (angular) filtering of sound beams by sonic crystal

     Pico Vila, Rubén; Pérez Arjona, Isabel; Sánchez Morcillo, Victor José; Staliunas, Kestutis
    Applied acoustics
    Date of publication: 2013-07
    Journal article

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  • Spatial filtering by chirped photonic crystals

     Purlys, Vytautas; Maigyte, Lina; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Staliunas, Kestutis
    Physical review A
    Date of publication: 2013-03-11
    Journal article

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  • Unlocked evanescent waves in periodic structures

     Botey Cumella, Muriel; Cheng, Yu Chieh; Romero García, Vicenç; Pico Vila, Rubén; Herrero Simon, Ramon; Sánchez Morcillo, Victor José; Staliunas, Kestutis
    Optics letters
    Date of publication: 2013-06-01
    Journal article

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    We predict the existence of evanescent modes with unlocked phases in two-dimensional (2D) dielectric periodic structures. Contrary to what is known for one-dimensional structures, where evanescent fields lock to the host modulation, we show that in 2D systems a new class of evanescent modes exists with an unlocked real part of the wave vector. Hence, beams constructed from such unlocked evanescent waves can exhibit spatial effects. A significant focalization of a beam propagating within the band gap of a flat photonic crystal slab is also shown. The predicted phenomenon is expected to be generic for spatially modulated materials.

  • Parametric patterns in optical fiber ring nonlinear resonators

     Staliunas, Kestutis; Hang, Chao; Konotop, Vladimir V
    Physical review A
    Date of publication: 2013-08-26
    Journal article

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    We propose that parametrically excited patterns, also known as Faraday patterns, can be observed in nonlinear fiber resonators, where the coefficient of Kerr nonlinearity is periodically varying along the fiber in the resonators. We study the parametric instability analytically on the basis of the Floquet theory and also numerically by direct integration of the system. Instead of a classical Faraday wave excitation scenario, where modulation in time causes the formation of patterns in space, here we propose an inverted scenario, where the modulation in space excites the patterns in time. © 2013 American Physical Society.

  • Double-discrete solitons in fishnet arrays of optical fibers

     Staliunas, Kestutis; Malomed, Boris A.
    Physical review E: statistical, nonlinear, and soft matter physics
    Date of publication: 2013-08-21
    Journal article

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    We demonstrate that crossed arrays of optical fibers support the double-discrete linear and nonlinear propagation of light beams, in which not only the transverse coordinate (the fiber's number) is discrete, but also the longitudinal (propagation) coordinate, i.e., the number of the fiber-crossing site, is effectively discrete too. In the linear limit, this transmission regime features double-discrete self-collimation. The nonlinear fishnet arrays with both focusing and defocusing nonlinearities give rise to double-discrete spatial solitons. Solitons bifurcating from two different branches of the linear dispersion relation feature strong interactions and form composite states. In the continuum limit, the model of the nonlinear fishnet reduces to a system of coupled-mode equations similar to those describing Bragg gratings, but without the cross-phase-modulation terms. © 2013 American Physical Society.

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    Flat lensing in the visible frequency range by woodpile photonic crystals  Open access

     Maigyte, Lina; Purlys, Vytautas; Trull, Jose; Peckus, Martynas; Cojocaru, Crina Maria; Gailevicius, Darius; Malinauskas, Mangirdas; Staliunas, Kestutis
    Optics letters
    Date of publication: 2013-07-15
    Journal article

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    We experimentally demonstrate full two-dimensional focalization of light beams at visible frequencies by a three-dimensional woodpile photonic crystal. The focalization (the flat lensing) with focal distances of the order of 50¿70 µm is experimentally demonstrated. Experimental results are compared with numerical calculations and interpreted by harmonic expansion studies.

    We experimentally demonstrate full two-dimensional focalization of light beams at visible frequencies by a three-dimensional woodpile photonic crystal. The focalization (the flat lensing) with focal distances of the order of 50–70 µm is experimentally demonstrated. Experimental results are compared with numerical calculations and interpreted by harmonic expansion studies.

    Missatge de l'editorial: "This paper was published in Optical letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ol/fulltext.cfm?uri=ol-38-14-2376&id=258441. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law."

  • Negative diffraction by a periodically modulated loss

     Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Herrero Simon, Ramon; Maigyte, Lina; Pico Vila, Rubén; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06-26
    Presentation of work at congresses

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    We show how a periodic modulation of loss on the wavelength scale provides negative diffraction propagation. In particular, we consider a 2D square arrangement of lossy cylinders embedded in air, with no index contrast. The phase-shifts accumulated in propagation trough such a structure, with flat-flat interfaces, are then compensated by normal diffraction in air leading to a substantial focalization of a light beam behind the crystal. The transmitted light intensity map exhibits a window of high transmission as a result of anisotropic loss provided by the periodicity. The effect is accounted buy the dispersion curves obtained by a coupled mode expansion of Maxwell equations and numerical experiments. The predicted phenomenon is expected to be generic for spatially modulated materials, and indeed we show that the results can be extended to acoustics.

  • Diffraction control of reflected beam by chirped mirror

     Cheng, Yu Chieh; Peckus, Martynas; Kicas, S.; Trull, Jose; Cojocaru, Crina Maria; Vilaseca Alavedra, Ramon; Drazdys, R.; Staliunas, Kestutis
    Electro-Optical Remote Sensing, Photonic Technologies, and Applications; and Military Applications in Hyperspectral Imaging and High Spatial Resolution Sensing
    Presentation's date: 2013-04
    Presentation of work at congresses

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    We propose and demonstrate a novel functionality of chirped mirror for monochromatic light beams: a diffraction control in reflections resulting in focusing or imaging of beams. The chirped mirrors, commonly used for manipulating temporal profiles of pulses, here are applied for manipulating the spatial dispersion of a monochromatic beam. By penetrating into dielectric layers of chirped mirror, the monochromatic beam experiences the negative diffraction, therefore the beam diverge propagating in front and behind the structure in normal diffraction region can be compensated inside this structure with negative diffraction. The result is focusing or imaging of the reflected beam from a flat interface of chirped mirror without optical axis.

  • Focusing by a flat woodpile 3D photonic crystal

     Maigyte, Lina; Cojocaru, Crina Maria; Purlys, Vytautas; Trull, Jose; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    We investigate spatial propagation effect behind the Photonic Crystal under particular dispersion conditions, which lead to a near field focusing. We analyze and experimentally demonstrate full two-dimensional near field focusing of light beams at visible frequencies behind the flat three-dimensional woodpile photonic crystal. Experimental results correspond well with numerical FDTD calculations as well as with the mode expansion studies. The focusing distance of 50 - 70 µm behind the crystal is obtained.

  • Beam focusing in reflection from flat chirped mirrors

     Cheng, Yu Chieh; Peckus, Martynas; Kicas, S.; Trull, Jose; Cojocaru, Crina Maria; Vilaseca Alavedra, Ramon; Drazdys, R.; Staliunas, Kestutis
    Physical review A
    Date of publication: 2013-04-15
    Journal article

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    We propose and show by proof-of-principle calculations and experiments that beam focusing and imaging can be obtained in reflection from a flat interface of a micromodulated dielectric structure. We show, in particular, that a one-dimensionally modulated and chirped structure can focus a beam, performing an imaging of a light pattern, i.e., can act as a transversely invariant flat focusing mirror. 2013 American Physical Society.

  • Intrinsic beam shaping mechanism in spatially modulated broad area semiconductor amplifiers

     Radziunas, Mindaugas; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis
    Applied physics letters
    Date of publication: 2013-09-23
    Journal article

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    We investigate beam shaping in broad area semiconductor amplifiers induced by a 2-dimensional (longitudinal and lateral) periodic modulation of the pump on a scale of several microns. The study is performed by solving numerically a (2¿+¿1)-dimensional model for the semiconductor amplifier. We show that, under realistic conditions, the anisotropic gain induced by the pump periodicity can show narrow angular profile of enhanced gain of less than 1°, providing an intrinsic filtering mechanism and eventually improving the spatial beam quality.

  • 3D woodpile photonic crystal for focusing of light beams

     Maigyte, Lina; Cojocaru, Crina Maria; Purlys, Vytautas; Trull, Jose; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06-25
    Presentation of work at congresses

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    Control and enhancement of beam quality of broadarea semiconductor devices and arrays by multimode interference couplers and two-dimensional gain modulation  Open access

     Murad, M.; Sorel, M.; Herrero Simon, Ramon; Botey Cumella, Muriel; Marsh, J.H.; Staliunas, Kestutis
    High Power Diode Lasers and Systems Conference
    Presentation's date: 2013-10-16
    Presentation of work at congresses

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    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.

    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.

  • Beam focalization in reflection from chirped dielectric mirrors

     Kicas, S.; Cheng, Yu Chieh; Staliunas, Kestutis; Peckus, Martynas; Trull, Jose; Cojocaru, Crina Maria; Vilaseca Alavedra, Ramon; Drazdys, R.
    Optical Interference Coatings
    Presentation's date: 2013-06
    Presentation of work at congresses

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    A novel use of chirped mirrors for narrow beam focalization is proposed. Focusing in reflection from flat chirped mirror has been demonstrated numerically and experimentally. Analogy to temporal dispersion mirrors is discussed.

  • Theoretical study of beam quality improvement in spatially modulated broad area edge-emitting devices

     Radziunas, Mindaugas; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis
    European Conference on Lasers and Electro-Optics - International Quantum Electronics Conference
    Presentation's date: 2013-05-12
    Presentation of work at congresses

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    Broad area (BA) lasers and amplifiers are robust, compact and highly efficient devices for generation of high power beams. These beams, however, suffer from a poor spatial and temporal beam quality. The stabilization and shaping of the optical beams in BA devices can be achieved, for example, by injection of the optical beam at some angle to the longitudinal axis [1], by the external optical feedback from the corresponding off-axis mirror [2], or by special geometry of the device [3].

  • Focussing by a flat woodpile 3D photonic crystal

     Maigyte, Lina; Cojocaru, Crina Maria; Purlys, Vytautas; Trull, Jose; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Staliunas, Kestutis
    European Conference on Lasers and Electro-Optics - International Quantum Electronics Conference
    Presentation's date: 2013-05-15
    Presentation of work at congresses

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    In this paper we investigate spatial propagation effect behind the Photonic Crystal (PhC) with nontrivial dispersion properties, which leads to a near field focusing. We analyze and experimentally demonstrate full two-dimensional focus formation of light beams at visible frequencies behind the three-dimensional woodpile photonic crystal. Experimental results correspond well with numerical FDTD calculations as well as with the mode expansion studies. The focusing distance of 60-80 micrometers behind the crystal is obtained.

  • Chirped Photonic Crystals for Spatial Filtering of Light Beams

     Maigyte, Lina; Purlys, Vytautas; Gailevicius, Darius; Peckus, Martynas; Malinauskas, Mangirdas; Staliunas, Kestutis
    European Conference on Lasers and Electro-Optics - International Quantum Electronics Conference
    Presentation's date: 2013-05-15
    Presentation of work at congresses

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    We show, theoretically and experimentally that chirped photonic crystals (longitudinal period varies along the propagation direction) can provide a substantial spatial (angular) filtering of the light beams and can reach efficiencies up to 50%.

  • Near field focusing of beams reflected by flat mirror

     Cheng, Yu Chieh; Kicas, S.; Peckus, Martynas; Trull, Jose; Cojocaru, Crina Maria; Drazdys, R.; Vilaseca Alavedra, Ramon; Staliunas, Kestutis
    Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference
    Presentation's date: 2013-05-13
    Presentation of work at congresses

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    We predict generally that narrow beams can focus in reflection from the flat interface photonic structures, and we demonstrate the effect experimentally in particular realization,i.e. in reflection from one-dimensional chirped mirror with flat surface.

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    Beam shaping in spatially modulated broad-area semiconductor amplifiers  Open access

     Herrero Simon, Ramon; Botey Cumella, Muriel; Radziunas, Mindaugas; Staliunas, Kestutis
    Optics letters
    Date of publication: 2012-12-15
    Journal article

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    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, predicts a spatial (angular) filtering of the radiation, which leads to a substantial improvement of the spatial quality of the beam during amplification. Quantitative analysis of spatial filtering performance is presented based on numerical integration of the paraxial propagation model and on analytical estimations.

    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, predicts a spatial (angular) filtering of the radiation, which leads to a substantial improvement of the spatial quality of the beam during amplification. Quantitative analysis of spatial filtering performance is presented based on numerical integration of the paraxial propagation model and on analytical estimations.

    Missatge de l'editor: "This paper was published in Optics letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-37-24-5253. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law."

  • Spatial filtering of sound beams by sonic crystals

     Pico Vila, Rubén; Sánchez Morcillo, Victor José; Pérez-Arjona, I; Staliunas, Kestutis
    Applied acoustics
    Date of publication: 2012-04
    Journal article

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  • Manifestation of spatial filtering performed by 3D photonic crystals

     Maigyte, Lina; Gertus, T.; Peckus, Martynas; Trull, Jose; Cojocaru, Crina Maria; Staliunas, Kestutis; Sirutkaitis, Valdas
    Proceedings of SPIE, the International Society for Optical Engineering
    Date of publication: 2012-04-16
    Journal article

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  • Formation of X-pulses in periodically gain/loss modulated materials

     Loiko, Yury; Botey Cumella, Muriel; Herrero Simon, Ramon; Staliunas, Kestutis
    Optics express
    Date of publication: 2012-05-07
    Journal article

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  • Improving beam quality in broad area semiconductor amplifiers

     Herrero Simon, Ramon; Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Staliunas, Kestutis
    Proceedings of SPIE, the International Society for Optical Engineering
    Date of publication: 2012
    Journal article

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  • Woodpile photonic crystal for beam collimation

     Maigyte, Lina; Trull, Jose; Mizeikis, Vygantas; Malinauskas, Mangirdas; Juodkazis, S.; Cojocaru, Crina Maria; Rutkauskas, M.; Peckus, Martynas; Sirutkaitis, Valdas; Staliunas, Kestutis
    Proceedings of SPIE, the International Society for Optical Engineering
    Date of publication: 2012
    Journal article

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    Experimental demonstration of bistable phase locking in a photorefractive oscillator  Open access

     Kolpakov, S.; Silva, F.; de Valcarcel Gonzalvo, German Jose; ROLDAN, EUGENIO; Staliunas, Kestutis
    Physical review A
    Date of publication: 2012
    Journal article

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    We report experimental evidence of bistable phase locking in nonlinear optics, in particular, in a photorefractive oscillator emitting in few transverse modes. Bistable phase locking is a recently proposed method for converting a laserlike system, which is phase invariant, into a phase-bistable one by injecting a suitable spatially modulated monochromatic beam, resonant with the laser emission, into the optical cavity. We experimentally demonstrate that the emission on the fundamental TEM00 mode becomes phase bistable by injection of a beam with the shape of the TEM10 mode with appropriate frequency, in accordance with recent theoretical predictions [K. Staliunas et al., Phys. Rev. A 80, 025801 (2009)]. The experimental observations are supported by an analytical study of a few-transverse-mode photorefractive oscillator model.

  • Spatial "rocking" for improving the spatial quality of the beam of broad area semiconductor lasers

     Radziunas, Mindaugas; Staliunas, Kestutis
    Proceedings of SPIE, the International Society for Optical Engineering
    Date of publication: 2012
    Journal article

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  • Anisotropic subdiffractive solitons

     Herrero Simon, Ramon; Barashenkov, Igor V; Alexeeva, N.V.; Staliunas, Kestutis
    Chaos solitons and fractals
    Date of publication: 2012-12
    Journal article

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  • High-directional wave propagation in periodic loss modulated materials

     Pradeep Kumar, Nikhil; Botey Cumella, Muriel; Herrero Simon, Ramon; Loiko, Yury; Staliunas, Kestutis
    Photonics and nanostructures. Fundamentals and applications
    Date of publication: 2012-10
    Journal article

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    Formation of collimated sound beams by three-dimensional sonic crystals  Open access

     Cebrecos Ruiz, Alejandro; Romero García, Vicenç; Pico Vila, Rubén; Pérez Arjona, Isabel; Espinosa Duró, Virginia; Sánchez Morcillo, Victor José; Staliunas, Kestutis
    Journal of applied physics
    Date of publication: 2012
    Journal article

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    A theoretical and experimental study of the propagation of sound beams in- and behind three-dimensional sonic crystals at frequencies close to the band edges is presented. An efficient collimation of the beam behind the crystal is predicted and experimentally demonstrated. This effect could allow the design of sources of high spatial quality sound beams.

  • CONTROL DE LA DIFRACCON DE LA LUZ EN MEDIOS MODULADOS

     Font Garcia, Josep Lluís; Vilaseca Alavedra, Ramon; Cojocaru, Crina Maria; Trull, Jose; Staliunas, Kestutis
    Participation in a competitive project

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  • Woodpile photonic crystal for beam collimation

     Maigyte, Lina; Trull, Jose; Mizeikis, Vygantas; Malinauskas, Mangirdas; Juodkazis, S.; Cojocaru, Crina Maria; Rutkauskas, M.; Peckus, Martynas; Sirutkaitis, Valdas; Staliunas, Kestutis
    SPIE Photonics Europe: Optics, Photonics, and Digital Technologies for Multimedia
    Presentation's date: 2012
    Presentation of work at congresses

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  • Focusing of evanescent waves by modulated sonic structures

     Romero García, Vicenç; Pico Vila, Rubén; Sánchez Morcillo, Victor José; Botey Cumella, Muriel; Herrero Simon, Ramon; Chung, Yu-Chieh; Staliunas, Kestutis
    Electrical Transport and Optical Properties of Inhomogeneous Media
    Presentation's date: 2012-09-04
    Presentation of work at congresses

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  • Self-collimation and spatial filtering in 2D gain/loss periodic spatially modulated materials

     Botey Cumella, Muriel; Staliunas, Kestutis; Herrero Simon, Ramon; Vilaseca Alavedra, Ramon; Pradeep Kumar, Nikhil
    European Conference on Lasers and Electro-Optics - International Quantum Electronics Conference
    Presentation's date: 2012-05-24
    Presentation of work at congresses

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  • Manifestation of spatial filtering performed by 3D photonic crystals

     Maigyte, Lina; Trull, Jose; Cojocaru, Crina Maria; Gertus, T.; Peckus, Martynas; Staliunas, Kestutis; Sirutkaitis, Valdas
    SPIE Photonics Europe: Optics, Photonics, and Digital Technologies for Multimedia
    Presentation's date: 2012
    Presentation of work at congresses

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  • Focalization of evanescent beams

     Botey Cumella, Muriel; Cheng, Yu Chieh; Herrero Simon, Ramon; Romero García, Vicenç; Pico Vila, Rubén; Sánchez Morcillo, Victor José; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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    We predict and show the existence of unlocked evanescent waves in two dimensional periodic structures. In a one dimensional periodic structure an evanescent mode are located either at the center or at the boundary of the Brillouin Zone, and the real part of wave-vectors is locked either to zero or to the modulation vector of the periodicity. However, we report an unexpected observation that this is not the case in 2D or 3D PhCs where "unlocked" complex modes can be predicted. As an interesting consequence, due to their “complex” character, or, equivalently, due to their phase freedom, beams constructed from such evanescent waves can show focalization effects. Indeed, we numerically simulate the propagation of such beams in the bandgap of PhC slabs, and we find significant focalization.

  • Collimation and imaging behind a woodpile photonic crystal

     Maigyte, Lina; Cojocaru, Crina Maria; Trull, Jose; Peckus, Martynas; Mizeikis, Vygantas; Malinauskas, Mangirdas; Rutkauskas, M.; Juodkazis, S.; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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  • Spatial noise reduction in broad area semiconductors

     Herrero Simon, Ramon; Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Staliunas, Kestutis
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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  • Radiation from band-gap solitons

     Gaizauskas, E.; Savickas, A.; Staliunas, Kestutis
    Optics communications
    Date of publication: 2011-04-15
    Journal article

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    Ab initio dissipative solitons in an all-photonic crystal resonator  Open access

     Etrich, C.; Iliew, R.; Staliunas, Kestutis; Lederer, Falk; Egorov, Oleg A.
    Physical review A
    Date of publication: 2011-08-25
    Journal article

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    We identify dissipative solitons in a Kerr-nonlinear all-photonic crystal resonator by solving Maxwell’s equations directly. The photonic crystal allows for diffraction management, leading to solitons with unique properties. These results are compared to a mean-field model based on Bloch waves, finding excellent agreement even for a high-contrast photonic crystal. By adjusting the quality factor and resonance frequencies of the resonator, optimal Bloch cavity solitons in terms of width and pump energy are identified. In particular, the width is independent of the quality factor, in contrast to the usual homogeneous cavity.

  • Spatial optical solitons in microstructured cavities

     Egorov, Oleg A.; Iliew, R.; Etrich, C.; Staliunas, Kestutis; Lederer, Falk
    Applied physics B. Lasers and optics
    Date of publication: 2011-09
    Journal article

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    We present a detailed study of the dynamics of light in passive nonlinear resonators with shallow and deep intracavity periodic modulation of the refractive index in both longitudinal and transverse directions of the resonator. We investigate solutions localized in the transverse direction (so-called Bloch cavity solitons) by means of envelope equations for underlying linear Bloch modes and solving Maxwell’s equations directly. Using a round-trip model for forward and backward propagating waves we review different types of Bloch cavity solitons supported by both focusing (at normal diffraction) and defocussing (at anomalous diffraction) nonlinearities in a cavity with a weak-contrast modulation of the refractive index. Moreover, we identify Bloch cavity solitons in a Kerr-nonlinear all-photonic crystal resonator solving Maxwell’s equations directly. In order to analyze the properties of Bloch cavity solitons and to obtain analytical access we develop a modified meanfield model and prove its validity. In particular, we demonstrate a substantial narrowing of Bloch cavity solitons near the zero-diffraction regime. Adjusting the quality factor and resonance frequencies of the resonator optimal Bloch cavity solitons in terms of width and pump energy are identified.

    From the issue entitled "Special Issue "Selected papers in nonlinear dynamics in dissipative and discrete optical systems""

  • Research activities of the group on nonlinear dynamics, nonlinear optics and lasers (DONLL) at the universitat politècnica de catalunya (Campus de Terrassa)

     Tiana Alsina, Jordi; Zamora Munt, Jordi; Nistor, Ioan Cristian; Roppo, Vito; Maigyte, Lina; Aragoneses Aguado, Andres; Khumar, N.P.; Martinez Gonzalez, Maria Cristina; Fernandez Soler, Juanjo; Serrat Jurado, Carles; Font Garcia, Josep Lluís; Herrero Simon, Ramon; Cojocaru, Crina Maria; Trull, Jose; Masoller Alonso, Cristina; Staliunas, Kestutis; Torrent Serra, Maria Del Carmen; Garcia Ojalvo, Jorge; Vilaseca Alavedra, Ramon
    Óptica pura y aplicada
    Date of publication: 2011-06
    Journal article

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  • Goos-Hänchen shift in complex crystals

     Longhi, Stefano; Della Valle, Giuseppe; Staliunas, Kestutis
    Physical review A
    Date of publication: 2011-10-25
    Journal article

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    Removal of excitations of Bose-Einstein condensates by space- and time-modulated potentials  Open access

     Staliunas, Kestutis
    Physical review A
    Date of publication: 2011-07-29
    Journal article

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    We propose that periodically in space- and time-modulated potentials (dynamic lattices) can efficiently remove the excited (the high-energy and large momentum) components of the trapped Bose-Einstein condensates (BECs) and, consequently, can result in efficient cleaning of the BECs. We prove the idea by numerically solving the mean-field models (the Schrödinger equation for noninteracting condensates and the Gross-Pitaevskii equation for interacting condensates of repulsive atoms), and we evaluate parameters and conditions for the efficient removal of excitations.