108 research outputs found
Aygon (Jean-Pierre). Pictor in fabula. L'ecphrasis-descriptio dans les tragédies de Sénèque.
No full textLabeye Th. Aygon (Jean-Pierre). Pictor in fabula. L'ecphrasis-descriptio dans les tragédies de Sénèque.. In: Revue belge de philologie et d'histoire, tome 84, fasc. 1, 2006. Antiquité - Oudheid. pp. 150-151
Postfabrication trimming of CMOS-compatible athermal MZI by thermal annealing
No full textCMOS-compatible athermal MZI is postfabrication trimmed in wavelength from -0.15 to -5.15 nm using thermal annealing process from 400 to 530 °C. The MZI filter shows temperature dependence less than 2 pm/°C and the temperature dependence is maintained after the annealing process
CMOS-compatible athermal 400GHz-spaced MZI interleaver
No full text400GHz spaced MZI interleaver is designed and fabricated on a SOI wafer by fully CMOS compatible process. The width and length of the MZI are optimized to reduce the temperature-dependent wavelength shift without using a negative thermo-optic material
Towards nonlinear conversion from mid- to near-infrared wavelengths using Silicon Germanium waveguides
No full textWe demonstrate the design, fabrication and characterization of a highly nonlinear graded-index SiGe waveguide for the conversion of mid-infrared signals to the near-infrared. Using phase-matched four-wave mixing, we report the conversion of a signal at 2.65 µm to 1.77 µm using a pump at 2.12 µm
Composants optiques intégrés pour l'Interférométrie astronomique
No full textIt has been recently demonstrated that integrated optics could enhance accuracy, stability, and ease of use of stellar interferometry techniques. The subject of this thesis is the study of an optical component based on singlemode waveguides for the coherent recombining of optical beams coming trom four telescopes. Proposed architecture provides an instantaneous measurement of complex visibility of interferometric signaIs of the six possible pairs of telescopes over the H spectral transparency band of atmosphere. From caracterisation results obtained on devices ~ealized using silica on silicon technology, more complex components were designed for the second generation instrumentation projects of the VL TI (Very Large Telescope Interferometer) It is shown that proposed architecture ;an be extended to J and K spectral bands, can be applied for the recombination of beams coming from six and even eight telescopes and could also be applied to realise a fringe tracker.Cette thèse porte sur l'étude d'un composant optique à base de guides d'onde monomodes destiné à recombiner de manière cohérente les faisceaux provenant de quatre télescopes. L'architecture proposée permet de fournir une mesure instantanée de la visibilité et de la phase des tranges pour les six paires possibles de télescopes sur la bande H de transparence de l'atmosphère. A partir des résultats de caractérisation optique obtenus sur les dispositifs réalisés en technologie silice sur silicium, des composants plus complexes destinés aux projets d'instrumentation de seconde génération du VLTI (Very Large Telescope Interferometer) ont pu être étudiés. Il est notamment montré que l'architecture proposée est extensible aux bandes d'observation J et K et à la recombinaison de faisceaux issus de six voire huit télescopes, et peut être aussi avantageusement utilisée pour réaliser un suiveur de franges
Composants optiques intégrés pour l'Interférométrie astronomique
No full textIt has been recently demonstrated that integrated optics could enhance accuracy, stability, and ease of use of stellar interferometry techniques. The subject of this thesis is the study of an optical component based on singlemode waveguides for the coherent recombining of optical beams coming trom four telescopes. Proposed architecture provides an instantaneous measurement of complex visibility of interferometric signaIs of the six possible pairs of telescopes over the H spectral transparency band of atmosphere. From caracterisation results obtained on devices ~ealized using silica on silicon technology, more complex components were designed for the second generation instrumentation projects of the VL TI (Very Large Telescope Interferometer) It is shown that proposed architecture ;an be extended to J and K spectral bands, can be applied for the recombination of beams coming from six and even eight telescopes and could also be applied to realise a fringe tracker.Cette thèse porte sur l'étude d'un composant optique à base de guides d'onde monomodes destiné à recombiner de manière cohérente les faisceaux provenant de quatre télescopes. L'architecture proposée permet de fournir une mesure instantanée de la visibilité et de la phase des tranges pour les six paires possibles de télescopes sur la bande H de transparence de l'atmosphère. A partir des résultats de caractérisation optique obtenus sur les dispositifs réalisés en technologie silice sur silicium, des composants plus complexes destinés aux projets d'instrumentation de seconde génération du VLTI (Very Large Telescope Interferometer) ont pu être étudiés. Il est notamment montré que l'architecture proposée est extensible aux bandes d'observation J et K et à la recombinaison de faisceaux issus de six voire huit télescopes, et peut être aussi avantageusement utilisée pour réaliser un suiveur de franges
Silicon germanium platform enabling mid-infrared to near-infrared conversion for telecom and sensing applications
No full textThis paper presents the potential of silicon germanium waveguides in the nonlinear conversion of light from mid-infrared wavelengths to the telecom band utilizing four-wave mixing. Design aspects and first characterization results of fabricated devices are presented
Polarization insensitive wavelength conversion in a low-birefringence SiGe waveguide
No full textWe report the first demonstration of a single-pass dual-orthogonal-pump FWM-based wavelength conversion scheme in a silicon-based waveguide. The silicon germanium (SiGe) waveguide used was designed to exhibit strong TE/TM mode similarity across a broad wavelength range as well as a large nonlinear coefficient . A polarization dependent loss (PDL) of just 0.42 dB was measured and the conversion of 40 Gb/s DPSK signals was demonstrated with 1.5 dB power penalty at a bit error ratio (BER) of 10-9
All-optical phase regeneration with record PSA extinction ratio in a low-birefringence silicon germanium waveguide
No full textWe report a low-power continuous wave-pumped phase sensitive amplifier (PSA)-based phase regenerator implemented in a passive silicon-based waveguide. A polarization assisted-PSA, consisting of two orthogonally-polarized pumps and a phase-locked signal copolarized to one of them, was implemented in a low-birefringence silicon germanium (SiGe) waveguide. The strong TE/TM modal symmetry of the waveguide and its large nonlinear coefficient enabled the achievement of an extremely large phase sensitive extinction ratio of approximately 29 dB for a total input power of only 21.3 dBm. This SiGe-based PSA was used to demonstrate phase regeneration on a 20 Gb/s differential phase-shift keying signal, thereby reducing its error vector magnitude and phase error by three and six times respectively and enabling a bit-error ratio improvement of up to 2 dB
Theoritical and experimental study of optical coupling in optomechanical systems
No full textDans ce travail, nous étudions les résonateurs optomécaniques en forme d'anneaux suspendus et les résonateurs optomécaniques à base de guide d'onde sub-longueur d'onde (SWG - pour Sub-wavelength grating). La première approche présentée - les anneaux suspendus - sert d'introduction aux notions générales et aux techniques expérimentales.Dans une deuxième approche, nous proposons de co-intégrer des guides d'ondes SWG à l'intérieur d'une cavité Fabry-Perot. L'indice de réfraction d'un guide d'ondes SWG est périodique avec un pas beaucoup plus petit que la longueur d'onde, ce qui permet une propagation optique sans perte et sans effet de diffraction. Le milieu peut être considéré uniforme, avec un effet de moyennage sur son indice de réfraction.En particulier, nous mettons en évidence de nouveaux mécanismes optomécaniques issus du guide d'ondes SWG, et attendons un fort taux de couplage optomécanique.Tout au long de la thèse, l'étude systématique des propriétés optiques, mécaniques et optomécaniques de chaque structure est menée, sur la base de modèles analytiques simplifiés et de simulations numériques. La réalisation technologique des structures sur wafers silicium de 200 mm est présentée, ainsi que des caractérisations expérimentales optiques et optomécaniques.In this work, we study ring shaped suspended optomechanical resonators, and Sub-Wavelength Grating (SWG) based optomechanical resonators.The first approach presented - suspended ring resonators - serves as an introduction over general equations and experimental techniques.On a second approach, we propose to co-integrate SWG waveguides inside of a Fabry-Perot cavity. The refractive index of a SWG waveguide is periodic with a pitch way smaller than the wavelength, that results in a lossless propagation with no diffraction effects. The medium can be approximated as uniform, with an averaging effect over its refractive index.In particular, we evidence new optomechanical mechanisms arising from the SWG waveguide, and expect a strong optomechanical coupling strength.All along the thesis, a systematic optical, mechanical, and optomechanical study of each structure is conducted, both with simplified analytical models and numerical simulations. The technological realisation of the structures over 200 mm Silicon wafers is presented, along with optical and optomechanical experimental characterisations
- …
