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Lasers à blocage de modes à base de fils et de boîtes quantiques pour les télécommunications optiques

Abstract : Generation of short and high repetition rate pulses is crucial for modern communication systems. Moreover a low noise level is requested for achieving efficient systems. Semiconductor mode-locked lasers allow the generation of subpicosecond pulses at several hundreds of GHz. The use of a new generation of quantum structures with dashes and dots as active material for these lasers has led to very short and high frequency pulses with very low noise level, even lower than with the usual material, quantum wells. The CNRS laboratory Foton-INSA has long time experience in growing high quality InAs quantum dashes and dots on InP substrate. The goal of this thesis was to experiment these materials to achieve mode-locked lasers. During the work, as a first stage these materials have been characterised through techniques such as photoluminescence and electroluminescence measurements so as to select the most suitable structures. Then the lasers have been fabricated. They consist in two sections, one section for amplification, and the other used as a saturable absorber to allow mode-locking. Quantum dot lasers have exhibited unstable behaviour noted by a strong optical emission peak splitting depending on injection current. The origin of this phenomenon is attributed to quantum dot groups likely characterised by their size difference. Mode-locking has indeed been obtained with quantum dash lasers at 10.6 GHz and 41 GHz. Characterisation of the pulses revealed a great chirp. Indeed a single mode optical fibre, 545 m long, was necessary to compress the pulses and to reach duration as short as one picosecond. The measured noise level in these lasers is 30 times lower than the best results reported on quantum well devices.
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https://tel.archives-ouvertes.fr/tel-00630247
Contributor : Madhoussoudhana Dontabactouny <>
Submitted on : Friday, October 7, 2011 - 6:41:24 PM
Last modification on : Tuesday, January 12, 2021 - 4:42:05 PM
Long-term archiving on: : Sunday, January 8, 2012 - 2:35:32 AM

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  • HAL Id : tel-00630247, version 1

Citation

Madhoussoudhana Dontabactouny. Lasers à blocage de modes à base de fils et de boîtes quantiques pour les télécommunications optiques. Physique Atomique [physics.atom-ph]. INSA de Rennes; Université Européenne de Bretagne, 2010. Français. ⟨tel-00630247⟩

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