周期极化LiNbO3晶体中电极布置对反转畴扩张的影响

利用外加电场极化的方法,分别研究了三种不同方式布置的极化电极对C向切割LiNbO_{3< /sub>晶体极化反转畴扩张的影响.实验结果表明在相同极化条件下，当极化电极长度方向与六边 形反转畴一对边呈90°和0°角时，极化扩张速度分别为0.089μm/ms和0.011μm/ms.实验结果揭示，为了有效地控制极化占空比，在制备一维准相位匹配LiNbO3晶体时应 避免极化电极与六边形反转畴壁中一对边呈90°的情况. 关键词： 周期极化 极化扩张 准相位匹配}     

采用接触式极化法研制有机聚合物电光光波导调制器

结合器件的整体结构考虑，对接触式极化方法和工艺进行了研究，基于接触式极化法，设计并制作了聚合物电光光波导相位和偏振调制器。通过测量器件的偏振调制特性，在1550nm光波波长下，获得了最大电光系数为llpm／V，电光相位调制器的半波电压为45V。     

Blends of Poly(Buty1ene Terephthalate) with Thermotropic Liquid Crystalline Polyesters. Morphology and Thermal Behavior

Blends of poly(butylene terephthalate) with liquid crystalline poly (decamethylene 4, 4′-terephthaloyldioxydibenzoate) were studied in all the composition range by optical and electron microscopy and differential calorimetry. The morphology and phase transitions of the blends are markedly influenced by the composition and thermal history. The results suggest the occurrence of miscibility phenomena between the two components in the amorphous phase.     

NMR metabolomics to study the metabolic response of human osteoblasts to non-poled and poled poly (L-lactic) acid

Untargeted nuclear magnetic resonance (NMR) metabolomics was employed, for the first time to our knowledge, to characterize the metabolome of human osteoblast (HOb) cells and extracts in the presence of non-poled or negatively poled poly-L-lactic acid (PLLA). The metabolic response of these cells to this polymer, extensively used in bone regeneration strategies, may potentially translate into useful markers indicative of in vivo biomaterial performance. We present preliminary results of multivariate and univariate analysis of NMR spectra, which have shown the complementarity of lysed cells and extracts in terms of information on cell metabolome, and unveil that, irrespective of poling state, PLLA-grown cells seem to experience enhanced oxidative stress and activated energy metabolism, at the cost of storage lipids and glucose. Possible changes in protein and nucleic acid metabolisms were also suggested, as well as enhanced membrane biosynthesis. Therefore, the presence of PLLA seems to trigger cell catabolism and anti-oxidative protective mechanisms in HOb cells, while directing them towards cellular growth. This was not sufficient, however, to lead to a visible cell proliferation enhancement in the presence of PLLA, although a qualitative tendency for negatively poled PLLA to be more effective in sustaining cell growth than non-poled PLLA was suggested. These preliminary results indicate the potential of NMR metabolomics in enlightening cell metabolism in response to biomaterials and their properties, justifying further studies of the fine effects of poled PLLA on these and other cells of significance in tissue regeneration strategies.     

Nanodots and microwires of ZrO_2 grown on LaAlO_3 by photo-assisted metal–organic chemical vapor deposition

ZrO_2 nanodots are successfully prepared on LaAlO_3(LAO)(100) substrates by photo-assisted metal-organic chemical vapor deposition(MOCVD). It is indicated that the sizes and densities of ZrO_2 nanodots are controllable by modulating the growth temperature, oxygen partial pressure, and growth time. Meanwhile, the microwires are observed on the surfaces of substrates. It is found that there is an obvious competitive relationship between the nanodots and the microwires. In a growth temperature range from 500℃ to 660℃, the microwires turn longest and widest at 600℃, but in contrast, the nanodots grow into the smallest diameter at 600℃. This phenomenon could be illustrated by the energy barrier, decomposition rate of Zr(tmhd)_4, and mobility of atoms. In addition, growth time or oxygen partial pressure also affects the competitive relationship between the nanodots and the microwires. With increasing oxygen partial pressure from 451 Pa to 75_2 Pa,the microwires gradually grow larger while the nanodots become smaller. To further achieve the controllable growth, the coarsening effect of ZrO_2 is modified by varying the growth time, and the experimental results show that the coarsening effect of microwires is higher than that of nanodots by increasing the growth time to quickly minimize ZrO_2 energy density.     

激光二极管抽运被动调Q周期极化铌酸锂腔内倍频激光特性的研究

提出了将饱和吸收Cr^4 :YAG晶体被动调Q开关同时作为布儒斯特片在三镜V型折叠谐振腔中起像散补偿作用的腔内倍频设计方案。在连续激光二极管端面抽运情况下,给出了V型谐振腔结构光束束腰半径和位置、像散补偿Cr^4 ：YAG晶体的厚度和谐振腔折光角度的设计方法以及计算公式。采用周期极化铌酸锂晶体作为倍频元件,由于谐振腔内的基波和谐波具有相同的偏振办向,避免了腔内双折射引起的绿光噪声问题,得到了输出稳定的序列脉冲。在连续抽运功率为500 mW时,得到了平均功率12．7mW的脉冲绿光输出。     

Study on dipolar orientation and relaxation characteristics of guest-host polymers affected by corona poling parameters

The dipolar orientation and relaxation characteristics of guest-host polymers poled by corona poling have been studied in detail. The mechanisms of dipolar orientation affected by poling parameters (voltage, temperature, time and cooling velocity) in polymers have been analyzed by UV-Vis absorption spectra and microscope. The results show that with increasing poling voltage, the orientation order parameter increases to maximum and then drops. Also the same trend of orientation order parameter has been obtained with increasing poling temperature. While the orientation order parameter increases to saturation with increasing poling time. With the biexponential model analyzing, it is shown that the relaxation of dipolar orientation can be slowed by slowing the cooling velocity during the poling process.     

Optical Non‐Linearity from Montmorillonite Intercalated with a Chromophore‐Containing Dendritic Structure: A Self‐Assembly Approach

Chromophore‐containing dendritic structures (G1, G2) are utilized to intercalate layered silicates, which results in a large d‐spacing up to 126 Å. An exfoliated morphology is obtained by mixing the dendritic structure intercalated layered silicates with polyimide in N,N‐dimethylacetamide solution. The dendritic structures attached on the clay template would arrange in a non‐centrosymmetric manner. This self‐assembled arrangement brought about the electro‐optical coefficients of 5–6 pm · V⁻¹ for these relatively low chromophore‐containing organic/inorganic nanocomposites without resorting to poling. Excellent temporal stability (100 °C) is also achieved.

     

掺杂型聚合物的电晕极化特性及其机理研究

实验研究了聚甲基丙烯酸甲脂(PMMA)掺杂生色团分散红DR19的电光聚合物的电晕极化特性.结合吸收光谱法和显微镜形貌分析了极化电压、极化温度以及极化时间对极化效果的影响.理论和实验分析得出极化电压增大可以增大聚合物内部极化电场,但电压过大会引起薄膜击穿而降低极化效果;而极化温度升高可以增大分子取向力,但在聚合物玻璃化温度以上会导致相分离;极化时生色团分子的取向随时间增大并逐渐达到动态平衡.实验结果表明:表征极化效果的序参数随极化电压的增大而先增大后减小,随极化温度的升高而先增大后减小,随极化时间的增长先增大后趋于稳定.     

Theoretical Study for Wavelength Conversion of Cascaded Second-Order Nonlinearity in Silica Fiber

In this paper, A novel wavelength divison multiplexing (WDM) nets is proposed by use of cascaded second-order nonlinearities (⁽²⁾:⁽²⁾) in the D-fiber grating after periodically thermal/electric-field poling, and is theoretically analyzed for the first time. The coupled mode equations of the ⁽²⁾:⁽²⁾ nonlinearities are derived, and the analytic expressions for the electric-field amplitude of converted light wave and the conversion efficiency are obtained under the small signal approximation, which are well consistent with numerical calculations. Both analytic expressions and numerical results show that, under the phase matching, is proportional to the logarithm of the square of pump light power, and the 4th power of the grating length L and the second-order nonlinearity d. The calculated results also show that and of this fiber grating can be reached over -17dB and 120nm, respectively. With the increase of L, increases rapidly while decreases quickly. The results of simulated calculations and theoretical analysis show that the cascaded ⁽²⁾:⁽²⁾ process is different from quasi-phases-matched difference-frequency generation.