Exploració per autor "Roppo, Vito"

Ara es mostren els items 1-15 de 15

    • 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 ...

    • Cerenkov third-harmonic generation in chi((2)) nonlinear photonic crystal 

      Sheng, Yan; Wang, Wenjie; Shiloh, Roy; Roppo, Vito; Kong, Y.; Arie, Ady; Krolikowski, W. (2011-06-13)
      Article
      Accés obert
      We report on the observation of Čerenkov emission of a third-harmonic frequency in a two-dimensional nonlinear photonic crystal, where the second-order nonlinearity chi((2)) is spatially modulated by the reversal of ...

    • 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 ...

    • Harmonic generation in metallic, GaAs-filled nanocavities in the enhanced transmission regime at visible and UV wavelengths 

      Vincenti, M. A.; de Ceglia, D.; Roppo, Vito; Scalora, M. (2011-01-19)
      Article
      Accés obert
      We have conducted a theoretical study of harmonic generation from a silver grating having slits filled with GaAs. By working in the enhanced transmission regime, and by exploiting phase-locking between the pump and its ...

    • New propagation effects in semiconductors in the UV range: inhibition of absorption, negative refraction, anomalous momentum states, sub-wavelength imaging and non-plamonic nanometer-size guided waves 

      Scalora, M.; Vicenti, M.A.; Roppo, Vito; Foreman, John V.; Hans, Joseph W.; Akozeb, Neset; Bloemer, M.J. (2009)
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      We discuss new propagation effects in semiconductors at frequencies above the absorption including inhibition of linear absorption using phase-locked harmonic pulses, negative refraction, anomalous momentum states, ...

    • Phase locked second harmonic etalon localization 

      Roppo, Vito; D'Aguanno, G.; Cojocaru, Crina; Raineri, F.; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Raj, R; Scalora, M. (2009)
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      During the last decades a phase locking phenomenon has been observed for second harmonic (SH) generation but only recently it was recognized as such in systematic studies. The general solution of the SHG from a linear/nonlinear ...

    • 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 ...

    • Second-harmonic generation in disordered quadratic media: role of a ferroelectric domain structure 

      Roppo, Vito; Kalinowski, K.; Wang, W.; Cojocaru, Crina; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Scalora, M.; Krolikowski, Wieslaw; Kivshar, Yu. (2010)
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      We study theoretically the second harmonic generation in a nonlinear quadratic crystal with random distribution of ferroelectric domains. We show that the specific features of disordered domain structure greatly affect the ...

    • Second-harmonic generation in disordered quadratic media: role of a ferroelectric domain structure 

      Roppo, Vito; Kalinowski, K.; Wang, W.; Cojocaru, Crina; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Scalora, M.; Krolikowski, Wieslaw; Kivshar, Yu. (2010)
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      Naturally grown ferroelectric crystals such as Strontium Barium Niobate (SBN) often exhibit an irregular multidomain structure with rod-like domains [1]. These disordered nonlinear quadratic crystals have attracted a ...

    • Tailoring Cerenkov second-harmonic generation in bulk nonlinear photonic crystal 

      Sheng, Yan; Roppo, Vito; Kong, Qian; Kalinowski, K.; Wang, Qi; Cojocaru, Crina; Trull Silvestre, José Francisco; Krolikowski, W. (2011-07-01)
      Article
      Accés obert
      We investigate theoretically the Čerenkov-type second-harmonic generation in two-dimensional bulk nonlinear photonic crystal with longitudinal modulation of the χ(2) nonlinearity. We show that in this scheme the Čerenkov ...

    • The effect of domain distribution on second harmonic generation in disordered nonlinear media 

      Roppo, Vito; Saltiel, Salomon M.; Wang, W.; Kalinowski, K.; Trull Silvestre, José Francisco; Cojocaru, Crina; Neshev, Dragomir N.; Krolikowski, Wieslaw; Vilaseca Alavedra, Ramon; Staliunas, Kestutis; Kivshar, Yu. (2009)
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      We study theoretically and experimentally the second harmonic generation in nonlinear crystals with random distribution of ferroelectric domains. We show that the specific features of disordered domain structure greatly ...

    • The role of the phase locking phenomenon in the second and third harmonics cavity localization 

      Roppo, Vito; Cojocaru, Crina; D'Agunaro, G.; Ranieri, F.; Raj, R.; Trull Silvestre, José Francisco; Vilaseca Alavedra, Ramon; Scalora, M. (2009)
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      We theoretically and experimentally study how the phase-locking mechanism changes effective dispersion of the medium at the harmonic frequencies making them become localized inside a opaque cavity designed to be resonant ...

    • Theoretical study of Cerenkov-type second-harmonic generation in periodically poled ferroelectric crystals 

      Sheng, Yan; Kong, Qian; Roppo, Vito; Kalinowski, K.; Wang, Qi; Cojocaru, Crina; Krolikowski, W. (2012-03)
      Article
      Accés obert
      We study theoretically the Čerenkov-type second-harmonic generation by a Gaussian beam in quadratic nonlinear media with periodically reverted ferroelectric domains. In particular, we consider the role of fundamental ...

    • Third harmonic generation at 223 nm in the metallic regime of GaP 

      Roppo, Vito; Foreman, John V.; Akozbek, N; Vincenti, M. A.; Scalora, M. (2011-03-14)
      Article
      Accés obert
      We demonstrate second and third harmonic generation from a GaP substrate 500 μm thick. The second harmonic field is tuned at the absorption resonance at 335 nm, and the third harmonic signal is tuned at 223 nm, in a range ...