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Ara es mostren els items 6-25 de 38

    • Beam focalization by chirped mirrors 

      Cheng, Yu Chieh; Peckus, Martynas; Kicas, Simonas; Trull Silvestre, José Francisco; Cojocaru, Crina; Vilaseca Alavedra, Ramon; Drazdys, Ramutis; Staliunas, Kestutis (Optical Society of American (OSA), 2014)
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      A novel application of chirped dielectric mirrors for narrow beam focalization is proposed and demonstrated numerically and experimentally. Analogy to temporal dispersion compensation by chirped dielectric mirrors is discussed.

    • Broadband third harmonic generation in quadratic media with disordered ferroelectric domains 

      Kalinowski, K.; Roppo, Vito; Wang, W.; Neshev, Dragomir N.; Kong, Y.; Cojocaru, Crina; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Staliunas, Kestutis; Krolikowski, Wieslaw; Kivshar, Yu. (2010)
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      We study nonlinear frequency generation in media with random ferroelectric domain structure. We show that randomness enables one to realize broadband third harmonic generation via cascading of two second order quasi-phase ...

    • Cavity behavior of second and third harmonic inhomogeneous solutions of Maxwell’s equations 

      Roppo, Vito; Cojocaru, Crina; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Scalora, M. (2010)
      Article
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      We study second and third harmonic generation of ultrashort pulses in a cavity environment and focus on the role of a phase locking phenomenon that causes the pump to trap and drag the generated harmonic fields. The results ...

    • Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials 

      Wang, Bin; Switowski, K; Cojocaru, Crina; Roppo, V; Sheng, Yan; Escalora, M.; Kisielewski, J.; Pawlak, D.; Vilaseca Alavedra, Ramon; Akhouayri, H.; Krolikowski, Wieslaw; Trull Silvestre, José Francisco (2018-01-22)
      Article
      Accés obert
      We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. ...

    • Controlling the likelihood of rogue waves in an optically injected semiconductor laser via direct current modulation 

      Perrone, Sandro; Vilaseca Alavedra, Ramon; Zamora-Munt, Jordi; Masoller Alonso, Cristina (2014-03-06)
      Article
      Accés obert
      Extreme and rare events are nowadays the object of intensive research. Rogue waves are extreme waves that appear suddenly in many natural systems, even in apparently calm situations. Here we study numerically the rogue ...

    • Diffraction control of reflected beam by chirped mirror 

      Cheng, Yu Chieh; Peckus, Martynas; Kicas, S.; Trull Silvestre, José Francisco; Cojocaru, Crina; Vilaseca Alavedra, Ramon; Drazdys, R.; Staliunas, Kestutis (2013)
      Comunicació de congrés
      Accés restringit per política de l'editorial
      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 ...

    • Domain statistics analysis of random nonlinear crystals via second harmonic generation 

      Wang, Bingxia; Cojocaru, Crina; Krolikowski, Wieslaw; Switowski, K; Yan Sheng, Yan Sheng; Akhouayri, H.; Vilaseca Alavedra, Ramon; Scalora, Michael; Trull Silvestre, José Francisco (Institute of Electrical and Electronics Engineers (IEEE), 2017)
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      We demonstrate an indirect non-destructive optical method for the characterization of ferroelectric domain size and distribution based on the analysis of the generated second harmonic spatial distribution. This method is ...

    • Einstein : física, enginyeria i matemàtiques 

      Vilaseca Alavedra, Ramon (2004-09-15)
      Audiovisual
      Accés obert
      "L’any 2005 fou declarat Any Mundial de la Física. Coincideix amb el centenari de publicacions d’Albert Einstein sobre el moviment brownià, sobre els quanta de llum i sobre relativitat especial. Les idees d’Einstein ...

    • Einstein: física, tecnologia i matemàtiques 

      Vilaseca Alavedra, Ramon (2014-01-31)
      Altres
      Accés obert
      "L’any 2005 fou declarat Any Mundial de la Física. Coincideix amb el centenari de publicacions d’Albert Einstein sobre el moviment brownià, sobre els quanta de llum i sobre relativitat especial. Les idees d’Einstein ...

    • El láser, fuente de fenómenos y dinámicas no lineales 

      Vilaseca Alavedra, Ramon (2010-10-01)
      Article
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    • ELECTRICITAT I MAGNETISME (Examen 2n Quadr.) 

      Vilaseca Alavedra, Ramon (Universitat Politècnica de Catalunya, 2005-06-06)
      Examen
      Accés restringit a la comunitat UPC

    • Enhanced efficiency of the second harmonic inhomogeneous component in an opaque cavity 

      Roppo, Vito; Raineri, F.; Raj, R; Sagnes, I.; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Scalora, M.; Cojocaru, Crina (2011-05-15)
      Article
      Accés obert
      In this Letter, we experimentally demonstrate the enhancement of the inhomogeneous second harmonic conversion in the opaque region of a GaAs cavity with efficiencies of the order of 0.1% at 612nm, using 3 ps pump pulses ...

    • Entrevista del professor Ramon Vilaseca al professor Daniel Gauthier. 

      Gauthier, Daniel; Vilaseca Alavedra, Ramon (2012-04-17)
      Audiovisual
      Accés obert
      Talking & Researching

    • Experimental and theoretical study of second and third harmonic generation in amorphous silicon 

      Rodríguez Suñé, Laura; Scalora, Michael; Cojocaru, Crina; Akozbek, Neset; Vilaseca Alavedra, Ramon; Trull Silvestre, José Francisco (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2022)
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      We report contrasted experimental and theoretical results on second and third harmonic generation from an amorphous silicon nanolayer. We perform this study by analysing the harmonic optical signals generated when fs and ...

    • Flat focusing mirror 

      Cheng, Yu Chieh; Kicas, Simonas; Trull Silvestre, José Francisco; Peckus, Martynas; Cojocaru, Crina; Vilaseca Alavedra, Ramon; Drazdys, Ramutis; Staliunas, Kestutis (MACMILLAN PUBLISHERS LIMITED, 2014-09-17)
      Article
      Accés obert
      The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat ...

    • Flat focusing mirrors 

      Staliunas, Kestutis; Cheng, Yu-Chiech; Kicas, Simonas; Trull Silvestre, José Francisco; Cojocaru, Crina; Peckus, Martynas; Vilaseca Alavedra, Ramon; Drazdys, Ramutis (Institute of Electrical and Electronics Engineers (IEEE), 2015)
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      We present the flat focusing mirror - the dielectric mirrors capable to focus and image the narrow beams in reflections. The mirrors are flat, and transversally invariant, i.e. have no optical axis. We consider two different ...

    • Gain/loss periodic spatial modulated materials on a wavelength scale 

      Staliunas, Kestutis; Herrero Simon, Ramon; Vilaseca Alavedra, Ramon (IEEE Press. Institute of Electrical and Electronics Engineers, 2009-06-28)
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    • Harmonic generation from metal-oxide and metal-metal boundaries 

      Escalora, M.; Vincenti, M. A.; de Ceglia, Domenico; Akozbek, Neset; Bloemer, M. J.; De Angelis, C.; Haus, J.W.; Vilaseca Alavedra, Ramon; Trull Silvestre, José Francisco; Cojocaru, Crina (American Physical Society (APS), 2018-08-20)
      Article
      Accés obert
      We explore the outcomes of detailed microscopic models by calculating second- and third-harmonic generation from thin-film surfaces with discontinuous free-electron densities. These circumstances can occur in structures ...

    • Harmonic generation in the opaque region of GaAs: the role of the surface and magnetic nonlinearities 

      Rodríguez Suñé, Laura; Trull Silvestre, José Francisco; Escalora, M.; Vilaseca Alavedra, Ramon; Cojocaru, Crina (2019-08-29)
      Article
      Accés obert
      Phase-locked second and third harmonic generation in the opaque region of a GaAs wafer is experimentally observed and analyzed both in transmission and reflection. These harmonic components, which are generated close to ...

    • Large nonlinear efficiency enhancement in the visible and UV range from plasmonic gold nanogratings 

      Cojocaru, Crina; Mukhopadhyay, Shroddha; Rodríguez Suñé, Laura; Vicenti, Maria Antonietta; Vilaseca Alavedra, Ramon; Scalora, Michael; Trull Silvestre, José Francisco (Institute of Electrical and Electronics Engineers (IEEE), 2023)
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      We report a combined experimental/theoretical investigation on second and third harmonic generation from a plasmonic gold nanograting, that exhibits a plasmonic resonance in the near IR. The intense field localization leads ...