Modeling of the photopolymerization kinetics for self-written waveguides
Date Issued
2012
Date
2012
Author(s)
Yang, Yao-Yang
Abstract
Optical waveguides are commonly used in optical communications systems to act as signal transmission channels or logic gates in the photonic circuits. Among the methods of fabricating optical waveguides, the self-written waveguide is an emerging one which allows two optical fibers to be connected through the waveguides formed between them so as to reduce the loss at the connection joint. It is the advantage of very low cost and high efficiency particularly for optical interconnection applications.
But there is no perfect model so far that can well predict the profile of the written waveguide and the process of chemical reaction behind the whole process. In previous literatures, the ray tracing or beam propagation method as well as the threshold condition for the light intensity were used for the modeling of the waveguide forming process. However, the real chemical reaction, i.e., the photopolymerization kinetics was not considered, so only the tendency of profile after curing can be predicted. In this thesis, all of the factors including the propagation of light waves and the photopolymerization kinetics for forming self-written waveguides were considered. In the numerical simulation, the parameters from the real experimental parameters were used so as to calculate the temporal and spatial variations of the concentrations of both the photo-initiator and monomer.
Contrary to the threshold criteria used in previous literatures, the threshold criterion for determining the complete curing of the photosensitive resin is that the monomer concentration is reduced to 1/4 of its initial value to faithfully reflect the actual physics. With such a modeling method, the self-written waveguides formed by using two obliquely incident laser beams were also calculated. If the intensity of one beam is larger while the other is smaller, the waveguides will merge at the intersection point into a single waveguide written dominantly by the beam with the larger intensity. The results in this thesis agree with the experimental data from the previous literature better than their simulation results.
Subjects
Self-written waveguide
Type
thesis
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