| Summary: | 碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 107 === Azobenzene-containing holographic materials can be used in applications such as optical storage and optical display. The small molecular weight matrix has poor film formation stability but fast recording speed. Ionic bonding materials may have unstable molecular anisotropy, which may affect the establishment of surface relief gratings. Therefore, in the choice of materials, covalently bonded materials are preferred. The azobenzene-containing materials can be utilized as rewritable holographic storage media through laser-inducted cis-trans photoisomerization.
This study used AAB (4-Aminoazobenzene) as the photosensitive monomer and reacted into epoxy resin with BADGE (bisphenol A diglycidyl ether). They formed stable covalent bond. Then by adding BAA (Bis(3-aminopropyl)amine) as a hardener. It is desirable to prepare a high reaction rate like small molecular weight material and high diffraction efficiency like highly covalent bonding material.
Firstly, the molar ratio of azobenzene and matrix is 1:1. The maximum diffraction efficiency increased from 21.50% to 23.29% when the ring-opening reaction time was gradually increased from 14 h to 20 h under the same thickness. When the material reacted for 20h was added with 0.005%, 0.01%, and 0.05% hardener under the same thickness, the maximum diffraction efficiency decreased from 27.01% to 21.28%. The time required to achieve maximum diffraction efficiency increased from 372 seconds to 640 seconds.
Then, the molar ratio of azobenzene and matrix is 1.5:1. The surface relief gratings are light sensitive. It is difficult to measure the morphology when the height of surface reliefs are about 0.7 μm, and the formed grating is irregular. Ordered surface relief can be observed by using a film having a thickness of fewer than 1 μm. The grating height can reach about 0.2 μm when the film thickness is about 0.5 μm. At this time, the small molecule material may be affected by heat under the interference of laser light with an intensity of 50 mW. With the intensity of 25 mW, there was no significant change in the time to achieve a balance of each order of diffraction efficiency. It can be seen that under the interference of strong laser intensity, there is a certain influence on the formation of the grating.
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