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Microwave Mesoscopics Speckle and Phase Singularity Evolution for Diffusive and Localized Waves

Microwave Mesoscopics Speckle and Phase Singularity Evolution for Diffusive and Localized Waves. Patrick Sebbah Laboratoire de Physique de la Matière Condensée CNRS, Université de Nice, France Collaborators: A.Z. Genack , B. Hu, J. Klosner, S. Zhang, Queens College, CUNY, NY

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Microwave Mesoscopics Speckle and Phase Singularity Evolution for Diffusive and Localized Waves

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  1. Microwave MesoscopicsSpeckle and Phase Singularity Evolution for Diffusive and Localized Waves Patrick Sebbah Laboratoire de Physique de la Matière Condensée CNRS, Université de Nice, France Collaborators: A.Z. Genack , B. Hu, J. Klosner, S. Zhang, Queens College, CUNY, NY O. Legrand, F. Mortessagne, C. Vanneste, LPMC, Nice V. Freilikher, Bar Ilan, Israel, K.Yu.Bliokh, IRA, Ukraine,Yu.P.Bliokh,Technion, Israel.

  2. Im{E}   Re{E}  Speckle construction

  3. Speckle Pattern

  4. Diffusive Regime <T(L)>ℓ/L

  5. Localized Regime <T(L)>exp(-/L)

  6.  <1  >1 Δν    Localized Regime 17.0 17.1 17.2 GHz GHz Diffusive Regime Transmission Spectrum Degree of Spectral Overlap :  = <>/<>

  7. Motivation The statistics of the speckle pattern and its evolution are universal ? or rather They may reflect the changing character of radiation at the Anderson transition ?

  8. Experimental Setup  ~ 1 cm ~10GHz Medium: Polystyrene Spheres Diam~1cm n~1.4 Vol. Fraction 52% Copper Tube L=1 m Diam =7.5 cm

  9. Experimental Setup  ~ 1 cm ~10GHz Medium: Polystyrene Spheres Diam~1cm n~1.4 Vol. Fraction 52% Copper Tube L=1 m Diam =7.5 cm

  10. Experimental Setup

  11. Experimental Setup

  12. Speckle Field Intensity Phase

  13. Phase Singularities

  14. The field is Gaussian • P(I)= exp (-I) • … • CI = |CE|2 • - Short range correlation • - Speckle spots independent • - Self averaging pattern Speckle in the diffusive regime

  15. ? Diffusive Regime Localized Regime Localized Regime Diffusive vs. Localized

  16. Diffusive vs. Localized Probability distributions of the magnitude of phase gradient normalized by its ensemble average

  17. Speckle Evolution

  18. Probability distributions of normalized average displacement of singularities within one speckle pattern

  19. In Conclusion • Fundamental aspects of multiple scattering and transport through random media reveal themselves in some aspects of the speckle field. • While the statistics of static speckle patterns are generic, fluctuations in the change within speckle patterns are greatly enhanced in the localization regime. • Speckle evolution reflects the interaction with the underlying electromagnetic modes of the medium.

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