Application of Surface Relief Hologram Using Azobenzene Containing Polymer Film

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.     

Direct Fabrication of Surface Relief Holographic Diffusers in Azobenzene Polymer Films

We propose a direct fabrication of light diffusers using azobenzene polymer films. Holographic recordings of surface relief diffusers are formed on the polymer film by exposure to an Nd:YAG laser (532 nm) through source diffusion materials. No post-treatment is needed, and it can be erased by heating or irradiating uniform laser beam. Diffusion pattern can be controlled by the polarization of the laser. Transmittance of over 88% is obtained at the wavelength of 633 nm.     

Direct Fabrication Methods of Surface Relief Electro-Optic Gratings in Azo-Polymer Films

Two fabrication methods of surface relief electro-optic (EO) gratings in azo-polymer films are described: surface deformation by a continuous wave laser and laser ablation by a pulse laser. In the fabrication process, the periodic intensity modulation of laser beams is formed by an interference fringe or a phase mask. The surface relief EO grating is fabricated by poling the surface relief grating (SRG) after the SRG fabrication process. The linear dependence of an applied voltage in the modulation efficiency of the first-order diffraction beam is observed. The proposed methods are effective for highly-efficient surface relief EO grating fabrication.     

含咔唑与偶氮分散红共聚物的表面增强共振拉曼光谱研究

借助于表面增强共振拉曼光谱散射(SERRS)技术,研究了一种新型的偶氮聚合物材料侧链含咔唑与偶氮分散红共聚物(CAP)在化学沉积法制备的银膜表面的拉曼峰增强和吸附行为。实验结果显示,CAP在银表面的状态为: 聚合物通过咔唑单体中咔唑基团和偶氮单体中硝基与银膜衬底发生物理吸附,而聚合物的主链与衬底相距较远没有相互作用。可以推测,聚合物在衬底表面的这种状态将对偶氮光存储器件的稳定性和工作效率产生不良影响。     

间插取样光纤光栅多通道色散补偿器

对间插取样光纤光栅（ISFBG）进行了理论分析和仿真,给出了ISFBG的折射率表达式,提出了一种在较低的折射率调制深度条件下实现通道间平坦度较好的色散补偿器的制作方法.实验制作了由两个取样光纤光栅间插而成的10通道色散补偿器,其时延抖动大都小于20 ps,通道间平坦度小于1 dB.     

Numerical Analysis of Photoinduced Surface Relief Grating Formation by Particle Method

The time evolution of photoinduced surface relief grating formation on azobenzene polymer films is analyzed by particle method for fluid mechanics. The surface relief grating is grown by using two beams interference with various polarization states numerically and compared with experimental results. The force acted on the dipole by electromagnetic field and surface force are considered as the driving force for photoinduced mass transport. The improved surface tension model is proposed in order to calculate curvature coefficient. The numerical results are coincided with experimental results qualititatively.     

表面活性剂含量对全息聚合物分散液晶光栅电光特性的影响

研究了含表面活性剂Actyflon-G04的全息聚合物分散液晶透射光栅的表面形貌和电光特性,通过理论分析得出驱动电压和膜的锚定能及表面自由能的关系.实验结果表明,在Actyflon-G04含量为4wt%-8wt%时光栅相分离程度高,相界面平滑,聚合物层的致密度增加.光栅的衍射效率达到96%,接近理想值.实现了在提高光栅衍射效率的同时降低驱动电压,使光栅的电光特性得到改善.     

Replicated Polymer Light Guide Interconnector with Depth Modified Surface Relief Grating Couplers

Planar light guide plate with one in-coupling and N out-coupling surface relief gratings is designed to perform as optical backplane broadcasting system for board-to-board connections. The performance of the element is analyzed theoretically with rigorous electromagnetic theory and results are confirmed experimentally. In addition, optical backplane elements have been replicated using conventional injection molding and UV-replication techniques.     

连续CO2激光脉冲制作长周期光纤光栅的研究

利用耦合模理论分析了均匀长周期光纤光栅中的模式耦合, 描述了连续CO₂激光脉冲逐点写入长周期光纤光栅技术的实验研究情况, 实验中观测到模式耦合强度随光栅区域长度发生周期性变化.     

Temperature Dependence of Photoinduced Birefringence in an Azobenzene Polymer

The photoinduced birefringence in an azobenzene polymer is investigated at different temperatures between -20℃ to 50℃. It is found that there is a peak value of photoinduced birefringence in the temperature dependence of the photoinduced birefringence under a certain pumping intensity. With the pump light in 90mW/cm^2, the peak value of the photoinduced birefringence appeared at about 0℃ C. The effect of temperature on the photoinduced birefringence is discussed using the competition mechanism between the photoinduced reorientation and the thermal random motion.     

偶氮苯聚合物全息光栅衍射效率和偏振特性研究

研究了不同偏振全息模式下基于交联偶氮苯聚合物薄膜的相位光栅的形成机理、衍射效率和偏振特性.利用琼斯矢量表征了正交线偏振(SP)和半行线偏振(SS)干涉模式下的偏振干涉场.基于SP和SS两种模式,制作了无明显表成起伏的纯折射率光栅和有表面起伏的浮雕光栅.偏光显微镜(POM)观测说明纯折射率光栅具有周期性的折射率分布;近场光学显微镜(SNOM)探测说明纯折射率光栅和浮雕光栅的表而起伏在5 nm以下和 85.23 nm.实验表明.当探测光为水平偏振时,纯折射率光栅的衍射效率达到22.2%.浮雕光栅只能达到1.65%.纯折射率光栅的0、 1级衍射光分别为水平和竖直线偏振光,偏振度达到0.9969和0.9963;浮雕光栅的0, 1级衍射光均为水平线偏振光.     

Two-Photon Induced Anisotropy of Azobenzene Polymer Liquid Crystals Excited by a 532nm Laser

Polymer liquid crystals (PLC) with azobenzene moieties are promising materials for optical switching and image storage because the orientation of mesogens in thin films of this material may be modified by light.     

Two-Photon Induced Anisotropy of Azobenzene Polymer Liquid Crystals Excited by a 532 nm Laser

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A Novel Electro-Optic Polymer Modulator Based on Long Period Fiber Gratings

A novel high-speed electro-optic (EO) polymer modulator based on long period gratings (LPG) is designed. Using the theory of multi-cladding optical waveguide, we achieved relationship between modulate voltage and LPG’s resonant wavelength.     

nmSiO2对聚合物光纤光栅封装材料的改性研究

分析了刚性纳米粒子改性聚合物的原理，重点分析了nmSiO₂/硅氧烷（硅橡胶）复合材料的改性机理,采用120号溶剂性汽油为分散剂，通过共混法制得nmSiO₂—乙烯基硅氧烷、含氢硅氧烷硫化而成的复合材料,用AJ-Ⅲ_a型原子力显微镜分析研究了该材料的组团结构并测试了其力学性能,结果表明，硅氧烷橡胶改性后，材料的弹性模量增加了15.4%；拉伸强度增加了19.4%；扯断伸长率增加了30%,用改性后的硅氧烷聚合物材料封装光纤Bragg光栅(FBG)压力传感器，可有效改善封装材料与光纤光栅的耦联性能；通过粒子含量控制可以增韧增强硅氧烷，从而可制作变量程压力传感器，同时可以延长传感器的使用寿命,     

新型偶氮苯侧链共聚物的超快光致双折射特性

采用抽运探测方法测量了一种新型的含 4 偶氮苯 4′ 偶氮苯酚侧链的共聚物 (DAP PGMA)的光致异构特性。实验结果表明DAP PGMA比含单偶氮苯侧链共聚物P (MMA co MAZ)有较大的光致双折射效应 ,Δn～ 6 .6 0× 10 -4 ;同时DAP PGMA比P(MMA co MAZ)具有更快的开启速度 ,光致向向异性上升时间为 40 ps,这种皮秒量级的快过程对应于双偶氮苯生色团的顺反异构过程。     

新型含偶氮聚合物薄膜表面微结构的刻写研究

基于偶氮苯聚合物的光致异构和光致取向特性,开展了双偶氮苯功能化聚合物薄膜表面微结构的"刻写"研究.利用两束相干光照射,在样品表面"刻写"出了亚微米量级的光栅结构;利用分步法在样品表面制作出了清晰的"三角格子"等花样微结构,证明了双偶氮苯功能化聚合物对于表面微结构的制作有较强的可操作性.通过对比单偶氮和双偶氮材料的实验结果,证明了双偶氮聚合物具有响应时间快、衍射效率高等特点,并由此讨论了偶氮苯聚合物薄膜表面微结构的形成机理及其偏振选择性.     

非对称切趾对啁啾光纤光栅特性优化的分析

基于对啁啾光纤布拉格光栅反射谱和时延曲线的分析,引入非对称切趾技术。综合时延曲线纹波和反射谱纹波平滑两方面考虑,将对称切趾技术的最佳切趾比例、左移和右移两种非对称切趾技术以及采用不同切趾函数对光纤光栅特性参量的优化效果进行了分析和比较。结果表明,与对称切趾相比,左移非对称切趾可避免对称切趾中为增大反射谱带宽而减小切趾比例使时延纹波增大的缺点,在保持反射谱纹波基本不变的前提下将时延曲线纹波降低了43.5%(与实验结果39.9%相吻合)。此外,与仅用汉明函数切趾相比,光纤光栅左端采用超高斯函数、右端采用汉明函数的非对称切趾方式使反射谱平坦部分纹波减小了89.3%,对应的时延曲线拟合误差减小了16.7%,获得了更好的优化效果。     

透明导电薄膜ITO对浅面浮雕VCSEL的影响

对于顶面出光的浅面浮雕VCSEL结构,有源区的电流密度分布的不均性制约着单模稳定性的提高。为此,提出了一种新型结构:氧化铟锡透明导电薄膜(ITO)浅面浮雕VCSEL。该结构不仅能够增大高阶模式的阈值增益,还能够提高基模的增益,实现基模对高阶模式的稳定抑制。研究了ITO的厚度对阈值增益的影响及ITO对VCSEL有源区电流密度分布的影响。研究结果表明:在ITO的厚度为半波长的整数倍时,基模对高阶模式的限制作用最强;ITO通过改善VCSEL有源区的电流密度分布,达到了增大基模的增益和降低高阶模式增益的目的,同时还降低了串联电阻和外电压。