<  Back to the Polytechnique Montréal portal

Design, fabrication and characterization of DWDM by sol-gel

Shahram Alavian

PhD thesis (2001)

[img]
Preview
Published Version
Terms of Use: All rights reserved.
Download (5MB)
Cite this document: Alavian, S. (2001). Design, fabrication and characterization of DWDM by sol-gel (PhD thesis, École Polytechnique de Montréal). Retrieved from https://publications.polymtl.ca/8617/
Show abstract Hide abstract

Abstract

RÉSUMÉ Des simulations permettent de produire la réponse spectrale. Celle-ci est fonction des paramètres suivants : indices de réfraction du matériau, dimensions du guide d'onde, distance spectrale, nombre de canaux et la fréquence du canal central. Le matériau est préparé en utilisant la technique du sol-gel. Le processus implique deux matériaux avec deux indices de réfraction différents. Des gaufres de silicium seront utilisées comme substrat pour leur compatibilité avec la technologie des semi-conducteurs et l'optique intégrée. La méthode du réseau de phase (PAG) est choisie pour la conception de la puce photonique. La méthode de l'indice effectif est utilisée pour analyser le dispositif optique et ainsi réduire le problème de trois deux dimensions. La réponse spectrale du dispositif est simulée en utilisant la transformée de Fourier plutôt qu’un algorithme de propagation, car cette méthode est plus rapide. Les dimensions des guides d'onde canal sont choisis pour permettre un bon confinement optique de la lumière et une réduction des pertes dues au couplage avec les fibres d'entrée et de sortie ainsi que dans les régions courbées du circuit. Le couplage entre deux sorties adjacentes est calculé en utilisant la méthode de la propagation d'onde (WPM). Les différentes étapes de la conception sont les suivantes : - Calcul des modes optiques et leurs indices effectifs. - Calcul de la différence du chemin optique entre les canaux dans la région du réseau afin de déterminer la différence de phase nécessaire et la longueur du guide planaire. - Utilisation de la transformée de Fourier pour focaliser différentes longueurs d'onde dans différents canaux et analyse de leurs interférences. La distance spectrale du dispositif est de 2.25 nm. Les pertes d'isolation de deux canaux adjacents ("cross talk"), sont inférieures -25 dB. Les pertes d'insertion dues la conception sont inférieures -3dB. La différence en termes de pertes entre le canal central et un canal situé une extrémité, appelée uniformité du réseau de phase, est inférieures -3dB. La réponse spectrale du dispositif devrait être indépendante au changement de la température. ABSTRACT Sol-gel method of hybrid glass fabrication is investigated. A systematic method is presented and applied towards fabricating an arrayed waveguide grating (AWG). The method includes the production of a photo-mask for obtaining the resolution of waveguide fabrication and a novel method of calculation in prism coupling method. After a detailed review of the theory behind the design of AWGs, the parameters obtained from the sol-gel method are used towards a design of an AWG. Using the limits and variations in the sol-gel method a perturbation analysis is done to predict the output response of the device under these variations. - Before designing the layout of the photo-mask, losses due to the mode coupling between two adjacent channels, fiber to channel, bending, cross talk and star-couplers are analyzed to obtain the best geometry possible in order to produce the optimum response. It is found that the thickness variation affects greatly the crosstalk parameter. In cases where the thickness varies gradually over the grating region, the effect is to broaden the bandwidth. However, in cases where thickness varies stochastically, the effect is to raise the background noise level. Variations of the channel dimensions, when they occur globally, cause a shift in the output response. This shift depends on the difference in dimensions of the designed and fabricated channel. Any change in the sol-gel method causes a change in the refractive index of the material. If such a change is the same for both guiding and the cladding material, the effect is also a shift depending on the difference between the expected refractive indices expected and the actual refractive indices of both materials. The refractive index of the sol-gel hybrid materials depends greatly on temperature. This characteristic may be exploited to tune the device to the exact central wavelength, by changing the temperature and hence fixing the refractive indices. The dependence of the output response to all the variations are presented. The photo-mask of an AWG layout is designed. Using the sol-gel method, the actual device is fabricated and then tested. The measured results of the fabricated AWG are within the expected and predicted range. Good insertion loss and channel isolations have been achieved. Moreover, a novel propagation method is presented and applied to extract propagation constants and the output profiles of integrated photonics devices without neither solving the wave equation nor using the paraxial approximation. By approximating the variation of the field to 4th order, this method is applied to the case of a sol-gel multimode planar waveguide. Propagation constants and output profiles are extracted and are in good agreement with the values obtained from the analytical method. The case of a full π circular rotation of a single mode planar waveguide is also illustrated. Furthermore, a novel, low temperature, sol-gel method of fabrication for inorganic transparent films is proposed. Using this method, single-layer, crack free and transparent silica based films were fabricated. Fabrication of a silica sol-gel film with no doping produced single layer films with an average roughness of about 0.5 nm, for a surface area of 10 μm² was obtained. Titanium doped films for the purpose of the refractive index increase is also considered. The refractive index and the loss measurements for silica-titania films was 1.510 ± 0.001. The infrared absorption spectra for both silica and silica-titania films are presented. The results suggest that the densification between 100°C and 150°C produces little change in quality of the material. CONTENU Solgel method of glass fabrication for integrated optics -- Extracting fabrication parameters -- Design procedure -- Designing a DWDM -- Test and characterization -- Measurement steps -- Inorganic, single-layer and crack free films for integrated optical devices using sol-gel method of fabrication -- Analysis of integrated devices by a new propagation method.

Open Access document in PolyPublie
Additional Information: Le fichier PDF de ce document a été produit par Bibliothèque et Archives Canada selon les termes du programme Thèses Canada https://canada.on.worldcat.org/oclc/1017529855
Department: Département de génie électrique
Date Deposited: 04 Aug 2021 11:05
Last Modified: 03 Sep 2021 14:52
PolyPublie URL: https://publications.polymtl.ca/8617/

Statistics

Total downloads

Downloads per month in the last year

Origin of downloads

Repository Staff Only