2004 Fiscal Year Final Research Report Summary
Control of optical nano-structure of azo-benzene polymers and its application to diffractive optics
| Project/Area Number |
15360025
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
YATAGAI Toyohiko University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (90087445)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Masahide University of Tsukuba, Graduate School of Pure and Applied Sciences, Associate Professor, 大学院・数理物質科学研究科, 助教授 (30150874)
COLE James B University of Tsukuba, Graduate School of Systems and Information Engineering, Associate Professor, 大学院・システム情報工学研究科, 助教授 (20280901)
YASUNO Yoshiaki University of Tsukuba, Graduate School of Pure and Applied Sciences, Research Associate, 大学院・数理物質科学研究科, 助手 (10344871)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Surface relief grating / Photonic Crystals / Azo Benzen Polymers |
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| Research Abstract |
Surface relief holograms are fabricated by means of irradiation of laser interference patterns. The diffraction efficiency and the surface relief depth depend on the writing energy and the polarization of the writing laser beam. This structure is very stable at temperatures under glass transition temperature T_g. We proposed a new technique to control the surface relief structure. The electric charge was deposited on the surface relief grating in a corona-depositing poling setup in an oven. The first-order diffraction efficiency measured before and after corona discharge increased from about 0.24 % to about 28 %. This diffraction efficiency increase is mainly caused by the increase of the relief depth caused by the electric charge. The relief depth is increased from 20 nm to 350 nm by corona charging.
The formation and erasure of photoinduced surface relief gratings (SRGs) on azobenzene-containing polymers are simulated using a calculation model based on the moving-particle semi-implicit (MPS) method. For the convection calculation, an anisotropic diffusion model is proposed. The gradient force of the optical electric field and the influence of surface tension are considered as driving forces for photoinduced mass transport. The viscosity of polymer films changes with the light intensity in our model. Particle motions in SRG formation and erasure are calculated and the SRG pitch and polarization dependences of the SRG growing and erasing rates are investigated. These theoretical results coincide qualitatively with our experimental results.
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