Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers

M.Ing.Long distance optical communication systems experience a large degree of attenuation due to fibre losses, necessitating signal amplification. Erbium Doped Fibre Amplifiers (EDFAs) have found widespread use as all-fibre optical amplifiers, but exhibit unequal amplification of different wavelengths. Since the gain spectrum is signal-power and pump-power dependent, each EDFA spectrum may differ considerably, and a tuneable gain equalizer is required. A tuneable long-period grating (LPG) can be implemented as a gain equalizer for EDFAs. This dissertation deals with the design of an integrated optic version of the tuneable equalizing filter. The various components of which the device comprises, including optical couplers, Mach-Zehnder interferometers and an LPG, are investigated. The integrated optics designs of these components are then done using the BeamPROP software package. The use and optical properties of germania-doped silica as photosensitive waveguide material is studied. The production of the films for the gain equalizer, using electron-cyclotron resonance plasma-enhanced chemical vapour deposition, is discussed. Characterization of these films was carried out using spectroscopic ellipsometry and infrared spectroscopy. The optical constants, thickness, germania content and hydroxyl absorption was calculated using these measurements

Dépôt de couches minces par plasma haute densité à basse press influence de l'injection de silane sur la cinétique du dépôt et le propriétés de la silice.

In this thesis, the deposition of silica films from silane and oxygen in a high-density plasma system is investigated. The influence of the process parameters and silane injection system design on the material properties is studied using spectroscopic ellipsometry (SE), Fourier transform infrared spectroscopy (FTIR), transmission spectroscopy and atomic force microscopy (AFM). The gas phase is analyzed using optical emission spectroscopy (OES) and differentially pumped quadrupole mass spectrometry (QMS). The creation of H2O in the system and its incorporation into the film during deposition is studied using capillary jet injection of the silane precursor and measuring the Si-OH absorption in the deposited film at various points on the substrate. Gas flow simulations, using the Direct Simulation Monte Carlo (DSMC) technique, are used to model the fluxes of the species ont! o the substrate plane. The simulation shows that the flux of H2O onto the substrate holder is uniform while the silane flux varies along the substrate holder, which explains the experimentally observed lower level of silanol in the deposited film in the regions that have a high deposition rate. A comparison between the experimental and simulation results leads to the conclusion that high-density plasma deposition systems can only be considered as well mixed when no rapid removal of the gas phase species, such as SiH4, is present.Il s'agit de dépôt de silice utilisant le silane et l'oxygène dans un système plasma haute densité. L'influence des paramètres du procédé et du système d'injection du silane sur les propriétés des matériaux sont étudiés par ellipsométrie spectroscopique, spectroscopie infrarouge à transformée de Fourier, spectroscopie de transmission et microscopie à force atomique. On étudie la phase gazeuse par spectroscopie d'émission optique et spectrométrie de masse quadripolaire avec pompage différentiel. La création de l'eau dans le système et son incorporation dans les couches pendant le dépôt sont étudiées utilisant l'injection du silane par jet capillaire. L'absorption du Si-OH dans les couches est mesurée en différentes positions sur le substrat. Les simulations de flux de gaz par la technique simulation directe Monte-Carlo sont utilisées pour étudier le flux des espèces sur le porte substrat. On a trouvé que le flux de l'eau est uniforme tandis que le flux de silane varie sur le porte substrat, ce qui explique la faible quantité de silanol dans la couche dans les régions déposées à grande vitesse. Une comparaison entre les résultats expérimentaux et les simulations montre que les systèmes plasma haute densité peuvent seulement être considérés comme bien mélangés quand il n'y a pas une élimination rapide des espèces en phase gazeuse

Dépôt de couches minces par plasma haute densité à basse pression (influence de l'injection de silane sur la cinétique du dépôt et les propriétés de la silice)

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Capillary jet injection of SiH4 in the high density plasma chemical vapor deposition of SiO2

International audienc

A new approach to laser polishing and form correction of optical components

The increasing variety of optical components and materials, combined with stricter surface tolerance requirements, necessitate refining existing polishing processes and developing innovative new polishing solutions and metrology technologies. A fast, reproducible laser polishing process would offer considerable economic benefits over conventional mechanical polishing processes and interest a broad variety of optics manufacturers. In this work, a holistic approach is taken to address the various aspects of glass polishing and form correction via a novel laser polishing system design, the use of a measurement strategy that can be integrated inline and simulation results that are correlated with process parameter studies for different materials

A new approach to laser polishing and form correction of optical components

The increasing variety of optical components and materials, combined with stricter surface tolerance requirements, necessitate refining existing polishing processes and developing innovative new polishing solutions and metrology technologies. A fast, reproducible laser polishing process would offer considerable economic benefits over conventional mechanical polishing processes and interest a broad variety of optics manufacturers. In this work, a holistic approach is taken to address the various aspects of glass polishing and form correction via a novel laser polishing system design, the use of a measurement strategy that can be integrated inline and simulation results that are correlated with process parameter studies for different materials

Deposition of Ge-doped silica thin films for an integrated optic application using a matrix distributed electron cyclotron resonance PECVD reactor

International audienc

SSD detection on LIDT tested coated Fused Silica samples

Material changes and Sub-Surface Damage (SSD) under Laser Induced Damage Threshold (LIDT) testing sites were investigated on 3 diverse single layer coated transparent fused silica samples to obtain additional information on damage precursors on these samples. As a detection method, photothermal deflection technique utilizing a resonant UV laser beam was used. The local variations in UV absorption and probe beam transmittance due to previous exposure to high fluence laser pulses were strongly dependent on the coating itself and on the laser energy used during the LIDT testing. Also the obtained LIDT values differ from coating to coating. Detected effects on the coatings and substrate surface beneath ranged from small surface dislocations to complete coating damage with material transformations. Additional absorbing damage precursors were found close to the damaged sites

Deposition of dielectrics using a matrix distributed electron cyclotron resonance plasma enhanced chemical vapor deposition system

International audienc

Multilayer optical filters control by multi-channel kinetic ellipsometry

International audienc