Artificial polarization anomalies from holographic gratings

An aluminum reflection grating made holographically was found to display polarization anomalies when illuminated with p-polarized light. Additional anomalies were detected for both p- and s-polarizations after the grating was coated with a layer of dielectric (410 nm of photoresist). These new anomalies have been interpreted in terms of the optical guided modes of a thin film dielectric waveguide bounded on one side by metal and on the other by vacuum.     

Influence of auxiliary violet light on holographic kinetics at low and high recording intensities in bacteriorhodopsin film

The photochromic bacteriorhodopsin (BR) film can be used as a rewritable holographic recording medium. Due to the saturation absorption and the scattering and reflecting lights from the BR film, the grating contrast-ratio of the hologram is diminished during the hologram recording. When the intensity of the recording light is low, the influence of the saturation absorption and the scatter and reflection of BR film on the grating contrast-ratio is weak. But for the case of intense recording light, this influence is more serious. It is found that the influence of the auxiliary violet light on the holographic kinetics of diffraction efficiency is distinct under different recording intensities. At the low recording light intensity, the steady diffraction efficiency is increased and the peak diffraction efficiency is suppressed by the auxiliary violet light. But for intense recording light, the steady diffraction efficiency and the peak diffraction efficiency are both increased by the auxiliary violet light. Based on the two-state model of BR photochromism, we give a good theoretical explanation to the above phenomena.     

细菌视紫红质的光电特性

利用电沉积法在ITO导电玻璃上沉积的BR紫膜薄膜,制作ITO/BRPMFILM/PARYLENEFILM/AL电池结构系统。在可见光的照射下,光电池系统对光强的变化产生微分响应电流信号,其上升时间不随光强变化量大小而变;并且光电流与光强的变化量呈线性关系。但是与文献1不同的一点是:在光强以相等的改变量增大或减小时产生的正、反微分响应电流(与质子泵方向相比)幅值并不相等,而是存在一定关系。     

基于细菌视紫红质光子逻辑门的实验研究

研究了基于细菌视紫红质(简称BR或菌紫质)变种材料D96N的3种光逻辑操作.在633nm激发光照射下，菌紫质分子会被激发到M态，处于M态的菌紫质对412nm的紫光呈较大吸收，会抑制同时入射的紫光.选择合适的紫光强度，通过CCD观测被抑制的412nm检测光透射强度分布，模拟了“非”、“或非”、“与非”几种基本的光子逻辑操作. 关键词： 细菌视紫红质 光子逻辑门 互补抑制     

包含左手材料的四层平板波导中的光导模

研究一个芯子层是左手材料,其他三层由传统材料构成的四层平板光波导系统,利用图解法对各种TE偏振的导波模式的解进行详细分析.研究表明,四层左手材料光波导既能支持振荡导模,也能支持表面导模,与三层左手材料光波导相比较,此四层波导的导波模式呈现一些新的特性.对于中间传统材料层存在振荡场的情形:芯子层支持振荡导模的光波导中存在基模,并且高阶振荡导模出现模式缺失的性质;芯子层支持表面导模的光波导可以支持基模和多个高阶模式,并且存在模式兼并的性质.对于中间传统材料层存在衰减场的情形,此四层波导结构可等效为三层左手材料光波导.这些新的光波导传输性质对各种光波导器件的制作有潜在的应用价值.     

Reflection of a focused light beam in a medium with Kerr nonlinearity. I. Estimates in the paraxial-beam approximation

The reflection intensity in a nonlinear dielectric layer is calculated in the approximation of paraxial incident and reflected light beams. It is shown that reflection is mainly determined by discontinuities of the refractive-index on the boundaries. Unlike reflection by a linear dielectric layer, reflection by a nonlinear layer occurs with a three-time decrease in the effective reflection area and the corresponding broadening of the angular spectrum. The intensity of the reflected wave is comparable to that of an incident wave with nearly critical beam power.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 7, pp. 867–875, July, 1996.This work was supported by the International Science Foundation and the Russian Federation Government (projects MR1000 and MR1300).     

Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons(holes)in the device are collected by anode(cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination(BR)or geminate recombination(GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same.Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.     

On the investigation of temperature changes of ferroelectrics dielectric constant by studying intensity changes of light emitted at their surface

The temperature dependence of the light intensity emitted by the plasma layer generated at the surface of triglycine sulphate samples at alternating polarization has been investigated. The changes of intensity of the emitted light were found to correspond to the changes of the dielectric constant of triglycine sulphate. This phenomenon can be used to determine the ferroelectric phase-transition temperature and to investigate the changes of the dielectric constant of ferroelectrics by studying the light of plasma generated at their surfaces.     

基于胆红素荧光增强效应的锌离子探针特性研究

锌离子Zn^2+对胆红素BR有着显著的荧光增强效应,基于该荧光特性,利用紫外可见光吸收和稳态荧光光谱技术提出了一种BR作为荧光探针用于Zn^2+浓度检测的新方法,特别是首次采用在波长663和600nm处的稳态荧光强度比值方法系统地研究了其与锌离子浓度在0~90μmol·L^-1范围内变化的关系,与常用的单波长荧光强度探测方法比较,有效地避免了探针浓度变化及激发光强度变化等非目标因素的影响。实验研究结果发现BR荧光探针对Zn^2+的识别行为在0~20μmol·L^-1范围内,探针BR的荧光强度比值I663 nm/I600 nm与Zn^2+的浓度之间具备线性增长关系,尤其是0~10μmol·L^-1有非常好的线性关系,线性相关系数r=0.999 87,同时Zn^2+检测限为0.1μmol·L^-1。在20~90μmol·L^-1范围内,荧光强度比值I663 nm/I600 nm趋于饱和。研究发现对实时检测人体内的Zn^2+具有很好的应用前景。     

用一维光子带隙结构增强硫化镉双光子吸收研究

用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2／SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收（TPA）现象。实验结果表明：一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关,如周期,光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。     

不同记录光强下辅助紫光对菌紫质薄膜全息衍射效率的影响

具有光致变色效应的菌紫质薄膜可用作可擦重写型全息记录介质. 在全息记录过程中,由于菌紫质薄膜对记录光的散射和反射引起记录光栅对比度下降,当记录光较弱时,这种影响较小,可以忽略;但当记录光较强时,散射和反射光对记录光栅的影响很大,必须考虑它们对光栅对比度的影响才能对实验结果进行合理的解释. 实验发现在不同的记录光强下辅助紫光对衍射效率动力学曲线的影响不同,当记录光强较弱时,加入辅助紫光可以提高衍射效率的稳定值、抑制峰值;而当记录光强较强时,加入辅助紫光除了提高衍射效率的稳定值外,还可以提高衍射效率的峰值. 关键词： 菌紫质 衍射效率 干涉条纹对比度     

细菌视紫红质用于光子逻辑门的研究

本文对基于细菌视紫红质变种材料D96N的三种基本光逻辑操作进行了研究.随着入射黄光强度的增加,菌紫质对黄光的吸收呈饱和吸收特性,此时紫光的照射将会使此饱和吸收阈值增加.在黄光和紫光对样品的共同作用下,透射光强度会被调制,调制的程度取决于这两束光的相对强度以及被调制光波长.通过观测被调制的525nm检测光强度,我们模拟了几种基本的光子逻辑运算:“非”、“或”和“与”运算.     

Finite size effects on structure and magnetism in mass-selected CoPt nanoparticles

In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device.     

Design and Analysis of the Integrated Plasma Wave Micro-Optical Modulator/Switch

Feasibility of a new integrated amplitude modulator/switch operating up to the visible spectrum, based on the absorption of light due to the linear interaction of the incident laser and a two-dimensional plasma layer is demonstrated. Plasma layers are generated via the Muller effect at the waveguide's interfaces. A plasma wave is excited in the two-dimensional gas when it is illuminated by electromagnetic radiation. Thus, due to the energy transfer from the electromagnetic wave to the plasma wave, the output light intensity can be controlled. The device is capable of amplitude modulation of guided beams in dielectric waveguides. Analysis based on both full-classical and semiclassical approaches are performed and are compared.     

基于菌紫质F态的永久光存储研究

在线偏振飞秒激光激发下, 菌紫质通过双光子光化学反应可以生成具有永久光致各向异性的蓝移产物F₅₄₀态. 基于F₅₄₀态的永久光致各向异性, 通过调控飞秒激光空间光场分布, 可以在菌紫质薄膜中实现永久光信息存储. 本文使用纯相位型空间光调制器调制飞秒激光光场, 在物镜焦平面上生成光学点阵图案, 可以将信息快速记录在菌紫质薄膜中. 同时, 通过改变入射激光偏振方向, 可以实现偏振复用光存储, 这在高密度光存储和数据加密领域具有潜在应用.     

光谱学方法研究介质阻挡沿面放电辉光模式的电场分布

利用介质阻挡沿面放电装置,在低气压空气中实现了辉光放电模式。利用光电倍增管对放电发光信号进行检测,发现外加电压每半周期出现一个发光脉冲,并且正负半周期的光脉冲是不对称的。利用Photoshop软件处理放电的照片,研究发现平行于高压电极不同位置的发光强度基本相同,然而距离高压电极越远,发光强度减小。放电中总电场由外加电场和电介质积累的壁电荷电场共同决定,确定该电场具有重要意义。通过分析放电的发射光谱中N+₂(B 2Σ+_u→X 2Σ+_g)谱线391.4 nm和N₂的第二正带系(C 3Π_u→B 3Π_g)谱线337.1 nm的比值,可以定性地说明电场的分布。研究发现电场在高压电极附近较大而远离高压电极处较小。这些研究结果对沿面放电的数值模拟和工业应用具有重要的价值。     

非周期微纳结构增强有机发光二极管光耦合输出的研究进展

有机发光二极管（OLED）具有功耗低、重量轻、色域宽、响应时间快及对比度高等优点,在全彩平板显示和固态照明等领域均显现出巨大的应用潜力,受到人们的广泛关注.然而,较低的光输出效率使得器件的外量子效率远低于内量子效率,这严重制约了OLED器件的发展和应用.因此如何提高OLED器件的光耦合输出效率已成为备受关注的研究课题.本文主要介绍了采用非周期微纳结构提高OLED器件光耦合输出效率的最新研究进展,对随机微纳透镜结构、光散射介质层、聚合物多孔散射薄膜、随机凹凸波纹结构及随机褶皱结构等多种对器件亮度分布和光谱稳定性无明显影响的光耦合输出技术进行了总结和讨论.最后,对提高OLED器件光耦合输出研究做了总结和展望.     

细菌视紫红质膜的光吸收非线性特性研究

对细菌视紫红质（ＢＲ）膜的光学吸收非性进行了研究,分别测量了细菌视紫红质光照前后的光吸收谱,结果显示它的吸收发生了明显的变化。用Ｚ扫描法研究了它的光学非线性,理论计算的结果表明它具有较大的光学非线性系数,且测量它的透过率随光强变化的关系曲线和理论模拟发现它对６３２．８ｎｍ波和匠光具有饱和吸收特性。     

拉曼高光谱成像系统中光在奶粉层的穿透深度研究

拉曼高光谱成像技术不仅可以获取样本的空间分布信息,图像上每个像素点还包括了完整的光谱信息,因其信息量丰富的特点已在食品安全检测方面得到了应用。本研究探索拉曼高光谱成像系统中光在奶粉层中的穿透深度,以及采集参数和奶粉类型对穿透深度的影响。实验选取均匀奶粉层样品放置于厚度为5 mm的三聚氰胺样本之上,检测奶粉层厚度为0.8～4.0 mm时的三聚氰胺特征峰强度,以此评估光在奶粉层中的穿透性和信号衰减情况。结果显示当奶粉层厚度一定时,随着激光功率变大,拉曼特征峰值随之增加,此外更长的曝光时间也可以使拉曼信号得到增强。在激光功率不小于2 W且曝光时间不小于500 ms时,光在全脂奶粉层的穿透深度可达4 mm。奶粉层厚度在0.8～4.0 mm范围内,穿透奶粉层的拉曼信号随着奶粉层厚度增加呈指数式衰减。在激光功率为8 W、曝光时间为1 000 ms的条件下,光在全脂、低脂和脱脂奶粉层的穿透深度均达到了4 mm。在相同测量厚度下,通过脱脂奶粉层接收的拉曼信号弱于通过全脂和低脂奶粉层接收的拉曼信号强度。研究结果为拉曼高光谱检测中奶粉样品的前处理提供了有益参考。     

Stimulated light emission in dense fog confined inside a porous glass matrix

We report on light amplification through stimulated emission in a dielectrically disordered medium. Liquid fragments confined in the solid matrix of porous quartz layers result in a random fluctuation of the dielectric function, and dye molecules embedded in the voids yield optical gain. The level of opacity is tunable by the ambient vapor pressure of the dielectric substance. In the multiple scattering regime, a strong intensity enhancement of the dye emission accompanied by significant spectral narrowing is observed above the threshold for a layer being in the opalescence state.