Photoinduced optical activity of C<Subscript>70</Subscript> fullerene in organic solvents

We have experimentally studied for the first time the effect of photoinduced rotation of the plane of polarization for pulsed laser radiation in solutions of C₇₀ fullerene in organic solvents and their mixtures. We have shown that the effect is observed for elliptical polarization of the laser radiation and is absent for linear polarization. We present the results of a study of the nonlinear optical characteristics of the C₇₀ solutions. We discuss the physical mechanisms by which nonlinear gyrotropy is induced in solutions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 93–99, January–February, 2009.     

级联二阶非线性铌酸锂全光开关的研制

以基于准位相匹配和频与差频级联二阶非线性[X^(2)：X^(2)]基础上的全光开关的理论分析作指导,进行了周期极化铌酸锂晶体(PPLN)和退火质子交换光波导(APE)的实验制备,利用所研制的PPLN-APE器件,以自行研制的工作波长为1．54μm的被动调Q掺钴铝酸镁激光器作为控制光源,以工作波长为1．5μm的连续二极管激光器为信号光源进行了级联二阶非线性全光开关实验。当控制光峰值功率为3kw,信号光功率为1mW时,实现13％的开关效率,分析了进一步提高全光开关性能的途径。     

偶氮材料——乙基橙的光致双折射特性

将偶氮化合物乙基橙样品置于一对正交的偏振片之间，用一束激发光照射该样品，分别测量 在激发光的不同强度和不同偏振方向下探测光的透射功率，研究样品的双折射特性.实验表 明，透射光的饱和值和稳定值与激发光强成正比，且与激发光偏振方向有关，探测光与激发 光振动方向的夹角(θ)为45°时，其值最大；若θ不太小（>10°），sin²2θ 与透射光的饱和值、稳定值成线性关系.同时，利用巴俾涅补偿器对样品的双折射率差进 行了测量，分别得到了绿光激发前后的准确数值为1.11×10^-3和3.57×10 ^-3. 关键词： 偶氮 双折射 测量     

光致异构全光逻辑门理论与实验研究

基于双光抽运探测模型，利用偶氮苯聚合物光致异构和光致双折射效应，建立了全光逻辑门的理论分析模型，提出了一种新颖的全光逻辑门设计方案.该方案基于输入抽运光和信号光的强度或偏振态，设计了“与”门、“或”门、“异或”门和“异或非”门等基本功能的全光逻辑门.以掺杂分散红1(DR1)的聚甲基丙烯酸甲酯(PMMA)薄膜为样品进行实验，得到了比较好的逻辑门运算实验结果，与理论分析相符合.     

The effects of substrate temperature on ZnO-based resistive random access memory devices

Ag/ZnO/Zn/Pt structure resistive switching devices are prepared by radio frequency magnetron sputtering.The ZnO thin films are grown at room temperature and 400 C substrate temperature,respectively.By comparing the data,we find that the latter device displayed better stability in the repetitive switching cycle test,and the resistance ratio between a high resistance state and a low resistance state is correspondingly increased.After 104-s storage time measurement,this device exhibits a good retention property.Moreover,the operation voltages are very low:-0.3 V/-0.7 V(OFF state) and 0.3 V(ON state).A high-voltage forming process in the initial state is not required,and a multistep reset process is demonstrated.     

All-optical switchings of 3-hydroxyflavone in different solvents

3-hydroxyflavone （3-HF） is an organic molecule with an excited-stated intramolecular proton transfer （ESIPT） effect. All-optical switchings and beam deflections of 3-HF in three kinds of solvents （cyclohexane, ethanol and dimethyl sulfoxide） have been investigated by using the third-harmonic generation （355 nm） of a mode-locked Nd：YAG laser as a pump beam and a continuous-wave （cw） He-Ne laser （632.8 nm） as a probe beam. The nonlinear refractive indices of 3-HF in the three different solvents are determined by using the Z-scan technique under an ultraviolet （UV） pump beam at a wavelength of 355 nm. It has been found that the optical switching and beam deflection effects result from the change in refractive index of 3-HF under the irradiation of the pump beam. On the basis of the analyses of absorption spectra and fluorescence spectra, we conclude that the change in refractive index of 3-HF is due to not the thermal effect but the ESIPT effect of 3-HF under the pump beam. As the ESIPT is exceedingly fast, 3-HF might be an excellent candidate for high-speed optical switching.     

Packet switching start-stop bits generation based on bifurcation behavior of light in a micro ring resonator

This paper proposes the interesting nonlinear behavior of light known as bifurcation, where the use of such behavior in a micro ring resonator to form the secure digital codes for optical packet switching application is demonstrated. A new concept of the stop-start bits in an optical packet switching protocol is formed by using the bifurcation codes. Bifurcation is introduced when light is input into a nonlinear micro ring device, where the refractive index of an InGaAsP/InP is one of device parameters. The other parameters of the device are coupling coefficient (K) and the ring radius (R), where the ring radii used are ranged from 5 to 10 μm. Simulation results obtained have shown that the packet switching data can be secured by using the generated start-stop bits as the secured codes.     

Determination of kynurenic acid levels in rat brain microdialysis samples and changes in kynurenic acid levels induced by N‐acetylaspartic acid

The levels of kynurenic acid, an endogenous antagonist of α₇ nicotinic acetylcholine and N‐methyl‐D ‐aspartate receptors, were measured in microdialysis samples obtained from the prefrontal cortices of rats using column‐switching high‐performance liquid chromatography with fluorescence detection. When the perfusate was constantly infused at a rate of 1.0 μ/min, the in vitro recovery of kynurenic acid through the dialysis membrane was approximately 20.4%, and the precision was within 1.31%. Endogenous kynurenic acid in the microdialysis sample was clearly detected using column‐switching high‐performance liquid chromatography. As an application study, N‐acetyl‐L ‐aspartic acid, an endogenous metabolite and precursor of N‐acetyl‐L ‐aspartyl‐L ‐glutamic acid, which is an agonist of metabotropic glutamate receptors, was infused for 120 min through the microdialysis probe. The kynurenic acid level significantly increased during the infusion of N‐acetyl‐L ‐aspartic acid, suggesting that kynurenic acid might have some association with N‐acetyl‐L ‐aspartic acid in vivo. Copyright © 2009 John Wiley & Sons, Ltd.     

开关图的几个代数性质

首先对开关图的自同构群进行了研究,随即讨论了它的点传递性,并得到Calyley图的开关图依然是Cayley图.     

Electric-pulse-induced local conducting area and joule heating effect in VO2/Al2O3 films

We investigated the effect of an electric-pulse on the insulator–metal phase transition of VO₂/Al₂O₃ films using synchrotron-based infrared microspectroscopy. By monitoring the time-resolved optical response, we could demonstrate that local conducting areas are formed under the influence of the electric-pulse, and the Joule heat generated from the local current flow drives a consecutive thermal phase transition in the adjacent sample area.