光聚合高分子用於自發性生成波導之動力學數學模型化

Modeling of the photopolymerization kinetics for self-written waveguides

楊曜陽(Yao-Yang Yang)

指導教授 ： 黃鼎偉

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01375

摘要

光波導在近年來光通訊領域的使用上越趨普遍，可用來做為積體光學的通路或是邏輯閘，也可當作兩條光纖在對接時的橋梁。而在製作光波導的方法中，利用光照型有機高分子聚合物自發生成光波導的方法近年來正逐漸受到重視，特別它可用來連接兩條光纖的接合處，讓通過的光可以沿著光波導傳遞減少散失的能量，因為製作成本低並且效率高、並且可以沿著光行進方向生成波導，在光互聯的應用具有非常大的潛力。
只是此種製作流程在先前的實驗論文中並沒有考慮到其化學部分的變化的理論模擬方法可以預測其產生反應的過程與最後的形貌。目前可找到的參考文獻中大多都是用光束追跡法或光束傳播法來算出光強度分布作為聚合物固化的近似條件。而實際光聚合反應化學反應的過程未列入，因此只能模擬出大概的形貌及趨勢。在此論文中我將整個實驗過程中的入射光電場模態、起始劑和聚合物單體分子濃度的化學反應動力方程組都以數學模型做完整的架構，試圖將此種製作波導的方法找到最好的模擬架構。
而在此論文中，我將光波傳播的光束傳播法與光聚合樹脂固化的現象都以數學方程組耦合求解，藉此計算出起始劑和聚合物單體分子濃度在每個時間點的空間分布。和以往文獻所使用的方式不同的是，固化條件是設定為聚合物單體分子濃度降為原濃度0.25倍為準則。另外也進一步模擬斜向入射的兩道光束若能量不同時，其形成的光波導會在交會點合併而沿著能量較強的光束所生成的波導行進。模擬出的結果與參考論文的實際實驗結果吻合而且比其理論模擬的結果更接近實際的情況。

關鍵字

自發性生成波導 ； 光聚合 ； 高分子

並列摘要

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.

並列關鍵字

Self-written waveguide

參考文獻

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