Effect of Ag Nanoparticles on Optical Properties of R6G Doped PMMA Films

The composite PMMA films containing Ag nanoparticles and rhodamine 6G are prepared. We investigate the fluorescence properties and nonlinear optical properties of R6G/PMMA films influenced by Ag nanoparticles. The fluorescence enhancement factor is about 3.3. The corresponding nonlinear refractive index is measured to be -2.423 ×10^-8 esu using the Z-scan technique, which is much enhanced compared with the R6G/PMMA film. The results indicate that these enhancements are attributed to surface plasmon resonance of Ag nanoparticles.     

天然橡胶-黄腐酸的非均相接枝聚合

腐植酸是一种组份和结构很复杂的天然大分子。利用腐植酸中的自由基进行烯类单体在腐植酸上的接枝聚合反应,已有报道,但尚未见到腐植酸与双烯聚合物反应获得接枝聚合物的报道。巩县风化煤黄腐酸是腐植酸中分子量较小(M_n=1035)的部分,它的结构特点已进行过较详细的表征。本文以这种黄腐酸为原料,在60℃下,以苯为天然橡胶的溶剂,以水为黄腐酸的溶剂,以过氧化苯甲酰为引发剂,聚合得到了天然橡胶与黄腐酸的接枝聚合物,并对接枝聚合物进行了一些表征。     

双光子吸收材料二苯乙烯衍生物的合成及光谱性质

设计、合成并用红外光谱、1H NMR、元素分析表征了三种用于双光子吸收材料的二苯乙烯衍生物,4,4′-双(二苯氨基-反式-苯乙烯基)联苯(BPSBP),4,4′-双(二乙氨基-反式-苯乙烯基)联苯(BESBP)和4,4′-双(9-咔唑基-反式-苯乙烯基)联苯(BCSBP)。实验结果表明三者最强的单光子吸收出现在350～400 nm之间,且单光子吸收和荧光光谱中表现出明显的溶剂化显色效应,揭示了分子内对称电荷转移的本质,双光子荧光光谱则揭示了单光子和双光子吸收具有相同的发射机理。利用双光子上转换荧光法测试发现,三种双光子吸收材料在800 nm飞秒激光的激发下具有较大的吸收截面,分别为892,617和483 GM,这表明在双光子领域有潜在的应用价值。     

High-sensitivity temperature sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.     

Effects of Laser-Induced Heating on the Photoinduced Birefringence in Azobenzene-Side-Chain Copolymer

The photoinduced birefringence was observed in the polymer poly[2-(4-(4-cyanophenyl) diazenyl phenyloxy) ethoxyl methacrylate] with a cw 532nm laser. The az, obenz, ene polymer character has been studied under the con-ditions of various illuminating time and light intensities. By analysing the processes of reorientation, the egect of laser-induced heating has been introduced to the buildup of photoinduced birefringence in azobenzene-side-chain copolymer. The curves for the buildup of birefringence were fitted with a modified fimction, i.e., biexponential curves and Gaussian curves. The relationship among all the parameters has also been presented. With the modified fitting fimction, we obtain a better fitting result.     

A Simple Model to Describe the Requirement of Realizing All-Optical Poling

All-optical poling （AOP） of a crosslinkable polymer based on hexamethoxymethyl melamine （HMMM） and Disperse red 1 （DR-1） is investigated. It is＇found that the saturation second harmonic generation （SHG） intensity decreases significantly with the increase of the sample temperature from 33℃ to 63℃. From the perspective of energy equilibrium, the main factors of AOP are analysed, and by introducing the classical ideal gas model, a simple inequation is first deduced to describe the requirement of realizing AOP.     

基于DVD光头的双光子光致漂白三维光存储

基于现有的DVD光头物镜与音圈电机，根据光致漂白的双光子吸收气维光信息存储原理，以钛蓝宝石飞秒脉冲激光进行双光子光信息写入和读出，利用音圈电机进行选层，在新型光致漂白材料二苯乙烯衍生物中进行光致漂白二进制编码信息的存储和读出实验研究；实现了三层光信息存储，信息点间距和信息层间距分别为4μm和15μm；用Matlab软件读出信息的信号强度并对其进行了识别，识别结果与写入的二进制编码信息完全一致。实验证明了用DVD光头进行双光子三维光数据存储的可行性，表明双光子吸收光致漂白技术可以与现有CD／DVD兼容，为实现多层高密度和超高密度光信息存储打下基础。     

Spectroscopic Properties and Three-photon Absorption Induced Optical Limiting of Series of Novel Nonlinear Chromophores

合成了三种新的具有D-π-D型分子结构和延伸共轭长度的非线性生色团,溶剂化显色分析显示由于跃迁时在基态和激发态之间有较大的偶极矩变化从而表现出较强的分子内对称电荷转移的性质.探讨了这些非线性生色团的基于三光子吸收的光限幅效应,在波长为、1064 nm的纳秒脉冲的作用下,呈现较大的三光子吸收系数,相应的生色团分子的三光子吸收截面高达10-74 cm6s2数量级.     

Photo-induced Alignment Behavior of Azobenzene-containing Polymer Films with Different Cross-linking Degree

合成了带有不同取代基的偶氮苯基团和可交联丙烯酸基团的共聚物,并通过控制热聚合的反应条件获得一系列不同交联密度的聚合物薄膜. 红外光谱表征样品交联度是从0到32%. 不同交联密度的偶氮聚合物薄膜的光致取向行为的研究结果表明交联能够降低光致取向速率以及薄膜的最大透过率. 进一步的重复擦写实验还表明交联薄膜能够有效抑制在线偏光擦写过程中偶氮苯分子的趋光性质量迁移.