Analysis and control of heat transfer in laser induced thermal poling process of polymer thin film

聚合物薄膜激光诱导热极化过程传热分析与控制

• 批准号: 09450283
• 负责人: HOZAWA Mitsunori
• 金额: $ 3.07万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450283/
• 关键词: Nonlinear optical material; Polymer thin film; Laser induced thermal poling; Heat transfer; Thermal diffusivity; Dipole orientation; Numerical simulation; 非線形光学材料; 非線形工学材料; レーザー加熱ボーリング

We have focused on the development and the optimization of waveguide patterning process in nonlinear optical (NLO) polymer thin film by laser induced thermal poling. In this research, we have elucidated the following subjects.1) Measurement of the thermal diffusivity of NLO polymer thin film.Thermal properties of NW polymer are an important factor in the thermal poling process. To measure the thermal diffusivity of the nonlinear optical (NW) polymer thin film, we modified the experimental apparatus based on the photoacoustic method. PMMA with DR1 chromosphore side groups was synthesized as an NLO polymer. It was found that the thermal diffusivity is independent on film thickness and percentage of the chromosphore, but increases as the applied electric field increases. Also, the thermal diffusivity of the NLO polymer thin film decreases with temperature. Our apparatus has no capability to measure at high temperature, more than glass transition temperature (about 380K) which gives abrupt … More ly change in thermal diffusivity, It is desired to develop another method to measure thermal diffusivity at high temperature.2) Numerical simulation of laser induced thermal poling processWe have constructed three-dimensional simulation code to estimate temperature profile in NW polymer thin) film on thermal poling process. To elucidate optimized condition for uniform polarization profiles, we introduced the temperature dependence of dipole (in NLO molecule) orientation dynamics to our simulation code. Since there is no available model for dipole orientation dynamics, relaxation dynamics model was used. At first, Ar^+ laser (wavelength of 488 nm) was used as light source on simulation. The calculation results showed that smaller diameter of laser beam and slower scanning speed of laser give more uniform polarization profiles. Since absorption spectrum of thin film suggests that He-Ne laser (wavelength of 632 nm) illuminates the thin film more interior than Ar^+ laser, He-Ne laser results in higher and more uniform polarization profiles. It is necessary to measure the dipole orientation dynamics for polymer materials in an electric field. Less

重点研究了非线性光学(NLO)聚合物薄膜激光诱导热极化光波导图形化工艺的发展和优化。1)NLO聚合物薄膜热扩散率的测量。NW聚合物的热性质是热极化过程中的一个重要因素。为了测量非线性光学(NW)聚合物薄膜的热扩散率，我们改进了基于光声法的实验装置。合成了含DR1色球侧基的聚甲基丙烯酸甲酯作为一种非线性聚合物。结果表明，热扩散率与薄膜厚度和色球所占比例无关，但随外加电场的增大而增大。此外，NLO聚合物薄膜的热扩散率随温度的升高而降低。我们的仪器没有能力在高温下测量，只有玻璃化转变温度(约380K)才能产生突然的…2)激光诱导热极化过程的数值模拟我们已经建立了三维模拟程序来估算NW聚合物薄膜在热极化过程中的温度分布。为了阐明均匀极化分布的最佳条件，我们在模拟程序中引入了偶极子(在NLO分子中)取向动力学与温度的关系。由于偶极子取向动力学没有可用的模型，因此采用了松弛动力学模型。首先，采用波长为488 nm的Ar~+激光作为光源进行模拟。计算结果表明，较小的光束直径和较慢的激光扫描速度可以得到更均匀的偏振分布。由于薄膜的吸收光谱表明，波长为632 nm的He-Ne激光比Ar~(++)激光对薄膜的照射更深入，因此He-Ne激光的偏振分布更高、更均匀。测量聚合物材料在电场中的偶极取向动力学是很有必要的。较少