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Theses

Multiple light scattering in porous gallium phosphide

Abstract : This thesis presents an experimental study on multiple light scattering, with the necessary introductions: theoretical background and sample preparation. The emphasis is put on the effects of the multiple scattering of waves, i.e., where interference effects exist and are significant, in the search for Anderson localization.
In ensemble-averaged random media, there exists a cone of light, superimposed on the diffuse background, in the exact backscattering direction, due to the constructive interference of time-reversed paths. This enhanced backscattering cone gives information about the multiple scattering, and localization. The regime of multiple light scattering is studied in a porous semiconductor, gallium phosphide (GaP), known at present as the strongest scattering material for visible light. The effective refractive index of strongly-scattering porous GaP samples is determine through an angular-resolved transmission technique. Such a refractive index in the strong scattering regime does not follow the effective medium theories.
The most strongly scattering samples, close to the expected transition to the localization regime, still follow perfectly the diffusion results. The macroscopic anisotropy of the porous samples is studied, using stationary and dynamic techniques. In these samples light diffuses further and faster along the pores, than against. Porous GaP displays both strong scattering and strong anisotropy.
In the last part, the subject of the full capture of a light pulse inside a short cavity is considered. By dynamically adapting the reflectivity of the input coupler to the shape of the incident pulse, the light reflected from the cavity can be made to vanish by destructive interference. When no light is reflected off the cavity, all the incident power is coupled inside the cavity, within a single mode of narrow bandwidth. Both theory and measurements support the proposed scheme.
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https://tel.archives-ouvertes.fr/tel-00010200
Contributor : Boris Bret <>
Submitted on : Friday, September 23, 2005 - 11:05:11 AM
Last modification on : Thursday, April 11, 2019 - 1:11:18 AM
Long-term archiving on: : Friday, April 2, 2010 - 10:00:16 PM

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  • HAL Id : tel-00010200, version 1

Citation

Boris Bret. Multiple light scattering in porous gallium phosphide. Atomic Physics [physics.atom-ph]. Universiteit Twente, 2005. English. ⟨tel-00010200⟩

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