PQ/PMMA感光高分子之體積全像特性分析與改進

Abstract

在本論文中，根據對於PQ光化學機制之了解，致力於改進PQ/PMMA的體積全像特性。一方面透過了解PQ/PMMA中的光致折射率變化來源與光化學產物，提出適當的方法改進其特性；另一方面，根據PQ的光激發行為，提出適當的模型來說明與模擬PQ光致化學變化之行為，並應用模型於體積全像的特性分析，以期能夠透過模型分析，進一步改進材料全像記錄特性，如敏感度、動態範圍與工作波長，延伸材料的應用性。 首先我們根據體積全像應用的材料要求，設計並製備出PQ/PMMA感光高分子材料，並以不同光學實驗探討其光學特性，包括吸收光譜說明材料的工作波長、平整度與光致收縮實驗說明材料可用於體積全像應用；並以體積全像多工儲存實驗，測量動態儲存範圍與敏感度；並根據前人的研究，說明PQ/PMMA的光致折射率變化來源與提出PQ染料的光致激發模型，說明PQ染料在單波長曝光下的光致激發行為；根據模型結果，可設計光致吸收實驗測量PQ的材料參數，並說明PQ/PMMA的全像記錄特性。 前述光學實驗結果指出，可知PQ/PMMA為適用於體積全像應用之材料，但是其敏感度與動態範圍無法滿足前瞻性的應用，如光資訊儲存等；PQ/PMMA中的光致折射率變化的來源主要是PQ與MMA的一對一光化學產物，因此我們提出加入具有更多反應官能基的單體，以期能夠改善PQ/PMMA的體積全像特性，並根據實驗結果提出改良製程，形成PQ摻雜共基底塊材；透過製程的改良，全面性地提升PQ/PMMA與PQ摻雜共基底塊材的體積全像特性；實驗結果指出此改進方向是正確而有效的。 根據PQ染料的光化學機制，我們提出利用雙波長全像記錄法在PQ/PMMA記錄體積全像，此記錄法的特性在於可透過開關短波長光源之曝照，決定資訊光的寫入，具有選擇性記錄與非破壞性讀取的特性，特別適合用於厚材料的體積全像記錄，減少材料動態儲存範圍的浪費。首先根據其機制，提出雙波長曝光模型，說明在短波長光源與長波長光源同時曝照時，PQ的光致激發行為；根據模型，我們可設計雙波長光致吸收實驗測量材料對於不同光源的量子效率；然後根據模型與實驗說明，在短波長均勻光源與長波長資訊光源的同時曝照下，PQ/PMMA的體積全像記錄行為；模型與實驗結果指出要如何改進PQ/PMMA材料的體積全像特性，以及如何延伸此類材料的工作波長，有別於過去根據光化學產物為基礎的改進方法。

In this thesis, based on the photochemical scheme of PQ dye, we focus on the analyses and improvements of characteristics of Phenanthrenequinone-doped PMMA photopolymer in volume holographic recording. First of all, we elaborate the design strategy and preparation technique to fabricate a centimeter-scaled sample with low photo-induced shrinkage and high optical quality. The characteristics of the material in volume holographic recording are measured, such as dynamic range(M/#), sensitivity, and photo-induced shrinkage. The material is suitable for volume holographic applications. Base on the photo-chemical scheme, there are two clues for improving the dynamic range and sensitivity of our material. One is that the photoproduct, one-to-one combination of PQ and MMA monomer, induces refractive index change of the material. By adding multi-functional groups into the material, the dynamic range and sensitivity are improved. It is also shown that the concentration of multi-functional groups is increased by using the advanced fabrication procedure. Based the light-induced excitations of PQ, we propose a four-leveled model to describe the holographic recording dynamics of the material. According to the model, we can extend the range of wavelengths of recording light and explore another way to enhance the performance of the material. Therefore, the two-wavelength holographic recording is developed and demonstrated. The information can be selectively recorded by controlling the uniform illumination of UV gating beam. The information is non-volatile read by using red beam. We build a model to describe the photo-induced transitions of the dye during two-wavelength exposure. Base on agreements of the simulation and experimental results, the characteristics of the material can be further improved.