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Antoine Salomon

Two-dimensional photonic crystals in SOI and their coupling with a Bragg mirror

Published on 2 January 2007
Thesis presented in 2007

Similar to electronic crystals, photonic crystals are materials whose dielectric is modulated. Just like in electronic, where the periodical variation of the potential structures the electrons' energies dispersion, this modulation of the optical index structures the photons' energies dispersion. It is then possible to control light by forbidding certain energies, band or space directions. In addition, because of their high integration and their compatibility with conventional C-MOS type technologies, Silicon On Insulator (SOI) photonics crystals possesses a strong potential for the development of future electro-photonic chips. In this context, the object of this thesis woks was the study of SOI photonic crystals light sources and especially the coupling between two dimensional photonic crystal light sources and a Bragg mirror. In a first part, this work focuses on the theoretical and technological aspects of photonic crystals. We describe the physical principles, especially the band structure, of photonic crystals in order to exhibit the way they operate and their properties. Then we present the technological fabrication as well as optical characterization tools. In a second part, we report on the coupling between radiatives desexcitations and photonic crystals' optical modes. We demonstrate that by coupling to slow group velocity modes or cavity modes, an optical source at 1.1 µm can be achieved. The results obtained are in agreements with calculated band diagrams. Finally we investigate the coupling between a Bragg mirror and a two dimensional photonic crystal. More precisely, we study the impact of the coupling distance on light extraction and the quality factor (Q). We show that these two quantities are periodical functions of λ/2 of it. We also exhibit that, according to the coupling distance, it is possible to enhance light extraction and the Q, compared to the characteristics of the single crystal. At last we present the first realization of a device coupling a two dimensional photonic crystal and two Bragg mirrors.

Microcavity, Bragg Mirror, SOI, Slow Modes, Photonic Crystals

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