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Ara es mostren els items 110-129 de 161

    • Scattering properties of a PT dipole 

      Staliunas, Kestutis; Markos, P.; Kuzmiak, V. (2017-10-23)
      Article
      Accés obert
      Electromagnetic response of a PT dipole is studied both analytically and numerically. In the analytical approach, the dipole is represented by two point scatterers. Within the first Born approximation, the asymmetry of the ...

    • Second and third harmonic generation in disordered quadratic nonlinear media: application to short-pulse characterization 

      Roppo, Vito; Wang, W.; Kalinowski, K.; Vilaseca Alavedra, Ramon; Trull Silvestre, José Francisco; Cojocaru, Crina; Staliunas, Kestutis; Krolikowski, Wieslaw; Kivshar, Yu. (2010)
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      We study parametric frequency conversion in quadratic nonlinear media with disordered ferroelectric domains. We demonstrate that disorder allows realizing broadband second- and third-harmonic generation via cascading of ...

    • Self-cleaning in non-Hermitian linear multimode fibers 

      Akhter, Mohammad Nayeem; Herrero Simon, Ramon; Staliunas, Kestutis; Botey Cumella, Muriel (Institute of Electrical and Electronics Engineers (IEEE), 2023)
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      We propose a self-cleaning mechanism in linear non-Hermitian graded index multimode fibers. The proposal is based a unidirectional coupling among transverse modes, induced by the introduction of a non-Hermitian potential, ...

    • 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)
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      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)
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      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
      Accés obert
      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 ...

    • Self-induced Faraday instability laser 

      Perego, A.M.; Smirnov, Sergey V.; Staliunas, Kestutis; Churkin, D.V.; Wabnitz, Stefan (American Institute of Physics (AIP), 2018-05-22)
      Article
      Accés obert
      We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously caused by the presence of pump depletion, which leads to a periodic gain landscape for light propagating in the cavity. As ...

    • Sharp acoustic vortex focusing by Fresnel-spiral zone plates 

      Jimenez, Noe; Romero García, Vicenç; Garcia Raffi, Luis Miguel; Staliunas, Kestutis (2018-05-14)
      Article
      Accés obert
      We report the optimal focusing of acoustic vortex beams by using flat lenses based on a Fresnel- spiral diffraction grating. The flat lenses are designed by spiral-shaped Fresnel zone plates composed of one or several arms. ...

    • Signatures of light-beam spatial filtering in a three-dimensional photonic crystal 

      Maigyte, Lina; Gertus, T.; Peckus, Martynas; Trull Silvestre, José Francisco; Sirutkaitis, Valdas; Cojocaru, Crina; Staliunas, Kestutis (2010-08-13)
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      Accés obert
      We report experimental evidence of spatial filtering of light beams by three-dimensional, low-refraction-index-contrast photonic crystals. The photonic crystals were fabricated in a glass bulk, where the refraction index ...

    • 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)
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      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)
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      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 ...

    • Sound directivity by PT-symmetric acoustic dipoles 

      Magariyachi, Tetsu; Arias Casals, Helena; Herrero Simon, Ramon; Botey Cumella, Muriel; Staliunas, Kestutis (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2021)
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      The new physics of open-dissipative, non-Hermitian systems have become a fruitful playground to uncover novel physical phenomena, even in exotic or counterintuitive ways, especially in optics and, more recently, also in ...

    • Spatial filter realized by dielectrice waveguides 

      Lukošiunas, Ignas; Gailevicius, Darius; Staliunas, Kestutis (International Society for Photo-Optical Instrumentation Engineers (SPIE), 2022)
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      In this work, we introduce a spatial filtering mechanism that can be effectively utilized by photonic crystals. The phenomenon utterly expressed here is Rayleigh-Wood’s anomaly. Such a mechanism is realized and optimized ...

    • Spatial filtering by axisymmetric photonic crystals 

      Staliunas, Kestutis; Gailevicius, Darius; Purlys, Vytautas; Maigyte, Lina; Peckus, Martynas (Institute of Electrical and Electronics Engineers (IEEE), 2016)
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      Photonic crystals due to their angular bandgaps and quasi-bandgaps can provide spatial (angular) filtering of light. Two-dimensional photonic crystals (photonic structures modulated along the longitudinal and along one ...

    • Spatial filtering in broad area semiconductor laser using photonic crystal 

      Gawali, Sandeep Babu; Gailevicius, Darius; Purlys, Vytautas; Trull Silvestre, José Francisco; Cojocaru, Crina; Staliunas, Kestutis (2020)
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      In high power regimes, broad area semiconductor lasers usually suffer from poor beam quality due to their asymmetric beam divergence, large beam quality factor (M2) and from the absence of any intrinsic filtering mechanism ...

    • Spatial filtering in edge-emitting lasers by intracavity chirped photonic crystals 

      Gawali, Sandeep Babu; Medina Pardell, Judith; Gailevicius, D.; Purlys, Vytautas; Garre Werner, Guillermo; Cojocaru, Crina; Trull Silvestre, José Francisco; Botey Cumella, Muriel; Herrero Simon, Ramon; Montiel Ponsoda, Joan; Staliunas, Kestutis (2020-10-01)
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      Accés obert
      In this work, we report an experimental and numerical study of the intracavity spatial filtering in edge-emitting lasers using a chirped photonic crystal (PhC) as the filtering element in the near-field domain. We provide ...

    • Spatial filtering with photonic crystals 

      Maigyte, Lina; Staliunas, Kestutis (2015-03-01)
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      Accés restringit per política de l'editorial
      Photonic crystals are well known for their celebrated photonic band-gaps-the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic ...

    • Spatial Filters on Demand Based on Aperiodic Photonic Crystals 

      Gailevicius, Darius; Purlys, Vytautas; Peckus, Martynas; Gadonas, Roaldas; Staliunas, Kestutis (2017-08-01)
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      Accés obert
      Photonic Crystal spatial filters, apart from stand-alone spatial filtering function, can also suppress multi-transverse-mode operation in laser resonators. Here it is shown that such photonic crystals can be designed by ...

    • Spatial noise reduction in broad area semiconductors 

      Herrero Simon, Ramon; Botey Cumella, Muriel; Pradeep Kumar, Nikhil; Staliunas, Kestutis (IEEE, 2012)
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    • Spatial optical solitons in microstructured cavities 

      Egorov, Oleg A.; Iliew, R.; Etrich, C.; Staliunas, Kestutis; Lederer, Falk (2011-09)
      Article
      Accés restringit per política de l'editorial
      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 ...