Emission, scattering and localization of light in complex structures: From nanoantennas to disordered media

Abstract : Using nanostructures to confine light allows to increase the interaction between an emitter and electromagnetic radiation. In this thesis, we use a classical formalism (presented in Chap. 1) to describe this interaction in various contexts, that can be gathered in two parts (respectively Parts II and III).
First, we study the apparition of localized modes in the near field of complex metallic structures. We study numerically the spatial distribution of the local density of states (LDOS) in the vicinity of two different structures: gold nanoantennas and disordered metallic films. Our results allow us to discriminate between radiative and non-radiative modes. We introduce the concept of cross density of states (CDOS) to quantitatively study the intrinsic spatial coherence associated with the modal structure of a complex medium. We use the CDOS to demonstrate an overall spatial squeezing of the modes near the electric percolation of disordered metallic films.
Then, we focus on strongly scattering media. By illuminating such structures by a coherent source, one obtains a chaotic intensity pattern called speckle. First, we use a diagramatic method to demonstrate an anticorrelation between the reflected and transmitted speckle patterns in the case of a diffusive slab in the mesoscopic regime. Then, we study the C0 correlation, that appears the source is embedded inside the medium. We propose a general derivation of the equality between the C0 correlation and the normalized fluctuations of the LDOS, and emphasize the fundamental role of near-field interactions. Finally, we study two-dimensional disordered media in the Anderson localized regime. We observe the strong coupling regime between such a mode and a resonant scatterer, in excellent agreement with theoretical predictions.
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Submitted on : Friday, December 13, 2013 - 9:45:36 AM
Last modification on : Thursday, July 4, 2019 - 11:00:07 AM
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  • HAL Id : tel-00917876, version 1

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Alexandre Cazé. Emission, scattering and localization of light in complex structures: From nanoantennas to disordered media. Optics [physics.optics]. Université Pierre et Marie Curie - Paris VI, 2013. English. ⟨tel-00917876⟩

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