光互连模块中偶数大点阵64×64位相计算全息光栅的简化设计和分析

采用简化的综合设计方法，对偶数大点阵位相计算全息光栅进行了优化设计和分析，实验上研制出用于光互连模块的６４×６４大点阵位相计算全息光栅分束器，优化设计一维衍射效率为８０．１％，光强不均匀性小于０．３％。     

细菌视紫红质的自衍射效率与最佳入射角研究

研究了弱光强下细菌视紫红质膜(bR膜)的自衍射特性.给出了弱光强下相干光在bR膜中产生的振幅光栅光强分布模型，并用ysinαx近似表示透射光强分布，结果与实验吻合.给出了不同透射光强y与指数α的对应关系.结果表明，在bR膜及入射光波波长给定的情况下，入射光强越小，对应的α值越大，当入射光强为0.072/T(mW/cm2)时，α等于1.计算出不同入射光强和入射角下的自衍射效率.结果发现，对应于最大衍射效率的最佳入射角为2°.     

驻波情形的液体声光效应的理论与实验研究

模拟计算了液体声光衍射的贝塞尔函数,测量了不同质量分数NaCl溶液对激光的衍射效率和不同温度纯水对激光衍射的相对光强比,计算了不同质量分数NaCl溶液的声光相位延迟、声致折射率变化量幅值.结果表明:随着NaCl溶液质量分数的增加,声光衍射效率、相对光强比、声致折射率变化量幅值均不同程度下降,而温度对纯水的相对光强比影响很小.     

反射型体全息光栅对超短脉冲激光光束衍射的性质

在光栅记录介质色散效应的影响下,拓展Kogelnik的耦合波理论研究了反射型体全息光栅对偏振方向垂直和平行于入射面的超短脉冲激光光束衍射的性质。结果表明对于记录在LiNbO3光折变晶体中的体全息光栅,在色散效应、光栅参量和入射条件的共同影响下,光栅对偏振方向垂直于入射面的超短脉冲激光光束衍射的光谱带宽大于对偏振方向平行于入射面的超短脉冲激光光束衍射的光谱带宽,在不考虑光栅介质色散效应的影响时,它们都变大。进一步给出了衍射光的光谱带宽及光栅的衍射效率随入射脉冲的光谱带宽与光栅的光谱带宽比值的变化情况。     

点阵全息图衍射效率的测量

提出了测量点阵全息图衍射效率的测试方法和相应的光学系统,其优点在于巧妙让零级与正负二级不能进入聚光系统,只有正负一级可以被记录,并且这种测试方法不受被测点干涉条纹方向变化的影响。并给了几种点阵全息防伪标识的测试结果。     

在光致聚合物中采用脉冲激光记录全息图的记录条件研究

在蓝绿敏光致聚合物材料中,用532 nm激光器作为光源,在等光强不同重复频率和等重复频率不同光强条件下分别进行全息记录,用红光进行动态读出,获得两种记录条件下的衍射效率曲线.实验结果表明,在近连续脉冲光下进行全息记录时,较低重复频率和较低光强的脉冲激光能够明显提高光致聚合物光栅的最高衍射效率,通过优化脉冲激光的重复频率和平均光强,可以在材料中记录衍射效率最高的全息图.     

“冷沉积”的Ag-BaO薄膜在超短脉冲激光作用下的光电发射

研究了冷沉积制备条件下获得的Ag-BaO薄膜在超短激光脉冲串作用下的光电发射．得到Ag-BaO薄膜的阈值光强为10W/cm²，光量子效率达10^-4数量级．光电流密度与入射光强的关系主要表现为一段曲率随光强增大而逐步减小的曲线．其光量子效率是一个可变值，它的变化规律同入射光强及薄膜本身的性能有关 关键词：     

辅助紫光提高菌紫质全息衍射效率的实验和理论研究

由于菌紫质样品的饱和吸收特性，在全息记录中，当记录光强大于样品的饱和光强时，全息光栅透过率随记录光相位差的分布远离余弦型，因此衍射效率的稳定值很低.菌紫质样品在红光和紫光共同作用下存在着双光束互补抑制效应，紫光可以抑制红光的透过率，提高红光的饱和光强，使记录区域由非线性区移至线性区，从而使全息光栅透过率随记录光相位差的分布变为余弦型，可以有效地提高全息衍射效率.实验证明，辅助紫光大大提高了菌紫质样品全息衍射效率的稳定值.根据此原理，建立了三光束全息光存储系统，在红光记录全息图的同时加入辅助紫光，可以使全息图衍射效率及衍射像的像质得到提高. 关键词： 菌紫质 全息存储 衍射效率 饱和吸收     

线偏振高斯光束通过复合型衍射光栅的传输特性

提出一种集合浮雕和折射率周期分布调制的复合型衍射光栅,并利用角谱表示和严格的模式理论研究了线偏振高斯光束通过这种复合型衍射光栅的传输特性.数值计算结果表明,在光栅的同一透射深度处复合型衍射光栅光强的起伏频率要比浮雕型光栅光强的起伏频率小.最后使用复合型衍射光栅模型,研究了亚波长体积相位全息光栅的表面起伏和入射光束的束腰宽度对衍射效率的影响. 关键词： 复合型衍射光栅 亚波长体积相位全息光栅 高斯光束 严格模式理论     

拼接光栅缝隙对激光脉冲光强分布的影响

以拼接光栅作为色散元件的激光脉冲压缩器中,要求脉冲压缩光栅表面光强分布均匀、能量输出效率高。利用菲涅耳-基尔霍夫衍射原理对脉冲压缩光栅表面光强和远场光强分布进行了研究。计算了拼接光栅缝隙宽度对光栅表面光强变化量和远场光强极大值的影响。在利特罗角附近入射时发现激光脉冲光强分布与拼接光栅缝隙宽度相关,得出了光栅拼接缝隙宽度应控制在0.5 mm以内。适当提高缝隙衍射效率能够改善光强分布均匀性和提高光能量输出,提出了对拼接缝隙采用两次重复曝光以提高其衍射效率的方法。     

无衍射光经望远镜系统的变换

对于轴锥镜透镜产生的无衍射光，它的中心光斑半径和无衍射距离是固定的，一旦应用中要求新的光束参数，则只能再制造一个新的轴锥镜透镜。本语文提出了种用普通球面透镜望远为改变无衍射光束参数的新方法，该方法是基于无射光和环光源之间的透镜变换关系。无衍射光首先被望远系统的第一块透镜变换为一个环光源，第二块不同焦距的透镜再将该环光源变换为一个不同参数的新无衍射光。新的光束参数由两个透的焦距比值决定 。     

二维声光点阵偏转的高速干涉摄影研究

本文介绍了一种利用二维声光点阵偏转技术进行高速干涉摄影的原理和方法。通过二维声光点阵偏转器件,把带有干涉图的光斑(￠6mm～￠8mm)按时间顺序偏转为10×10的光斑点阵,并记录在一张底片上。用连续激光为光源,曝光时间为10~(-5)～3×10~(-6)秒可调,幅频达10~5幅/秒,并用这种方法来记录瞬态温度场的干涉图,进行原理实验研究。     

基于LD激发荧光粉白光光源的窄光束照明光学系统设计

蓝光半导体激光器激发荧光粉产生白光光源技术发展迅速，但由于大功率蓝光半导体激光器在快轴、慢轴方向的光场分布差别较大，使得日前激光照明整体光学性能仍旧较差，难以实现大规模推广应用。针对该问题，设计了一款高质量激光照明光学系统，基于蒙特卡洛光线追踪理论，对激光光束进行准直调控、均匀光斑整形以及对荧光片进行设计，使得整体光源模块各元件得到最佳整合，最终实现了窄光束激光照明。仿真结果表明:激光光源的光收集率达98.3%，激光光斑的不均匀度为1.7%，白光均匀度为98%，光斑是出射准直角为1.6°的方形窄光束白光光斑。     

Laser drilling of thick material using femtosecond pulse with a focus of dual-frequency beam

Laser drilling is one of the basic, most frequently performed, material removal processes. The drilling aspect ratio is theoretically limited by the size and the focal depth of the machining laser spot. The aspect ratio can be improved by using dual focus. In this paper we describe a focus of two different frequencies based on the longitudinal chromatic aberration arisen when polychromatic collimated light is incident on a positive lens element. In the experiments, a Ti:Sapphire laser of 800 nm wavelength and 150 fs pulse duration was used as a source. Two tightly focused laser spots few hundred micrometers apart from each other were formed by focusing a combined collimated laser beam which contains the fundamental optic frequency and the second harmonic optic frequency. The focus of dual-frequency beam was used to drill a 3 mm thick PMMA plate. The drilling aspect ratio of a dual-frequency beam was compared to that of a focus of single frequency beam. Experimental results reveal that dual-frequency beam increases the aspect ratio and improves the drilling quality in terms of profile of the produced features.     

基于连续激光的纳米结构研制

基于激光受激辐射损耗原理的远场光学超分辨成像技术,当圆形入射高斯激光经过涡旋相位板调制后,将转变为中心光强为零的圆环形光束,该形状的激光束与光敏聚合物作用,能够制备出具有一定功能的纳米结构。介绍了自主搭建的基于圆环连续激光光源的激光直写系统,以及利用该系统研制的复合纳米结构。当光源为532 nm连续激光输出时,与正性光刻胶作用,得到直径 < 50 nm的纳米柱复合结构,以及整齐均匀的纳米柱阵列结构;与负性光刻胶作用,得到直径 < 100 nm的纳米通道,以及整齐均匀的中央有纳米通道的微米柱复合结构阵列。当光源为405 nm连续光纤激光时,与正性光刻胶作用,也得到了直径小至153 nm的纳米柱复合结构及其阵列。这些纳米结构的基本单元尺寸都突破了光学“阿贝衍射极限”的限制,具有实用潜力。     

Self-grown fiber fabrication by two-photon photopolymerization

We demonstrate a new fiber growth mechanism in a photocurable resin by ultrafast laser illumination. A high-repetition rate (∼1 MHz) ultrafast laser beam at the wavelength of ∼523 nm was focused into an ultraviolet photocurable resin to trigger two-photon photopolymerization process. Time-resolved shadowgraphs and scattered light imaging revealed that the curing commenced in the neighborhood of the geometric focal point of the laser beam and that the fiber growth progressed mostly towards the laser source. The cured fiber was thinner and longer than the profile of the focused laser beam, facilitated by nonlinear propagation and absorption of the ultra-fast laser beam. The achieved aspect ratio of the fiber was higher than 180 with ∼10 μm mean diameter, and the average growth rate was up to ∼2 mm/s.     

Electro-optical measurement of longitudinal dispersion in turbulent pipe flow

An attempt was made to correlate light beam absorption with the longitudinal dispersion of ink in turbulent pipe flow. Ink was injected into water flowing in a 2.22 cm ID pipe and the light beam produced by a laser traversed the pipe through transparent sections. Light beam attenuation by the ink pulse was measured with a photodiode and recorded by various means. Attenuation was measured at two locations downstream of the injection point. Since the attenuation was calibrated for ink density, theoretical prediction of the ink density distribution and the resulting light attenuation at the points of laser traverse was produced. The theoretical density distribution was based on only the first order source of longitudinal dispersion: the velocity gradient. The comparison between theory and experiment shows that, over a wide range of turbulence, dispersion was almost entirely due to velocity gradient and can be conveniently measured by the light beam absorption technique.     

高重复频率触发模式皮秒扫描相机

讨论了高重复频率扫描电路的研制,利用此扫描电路研制了扫描相机,使用掺钛兰宝石激光器进行了时间分辨率的标定,使用半导体激光器作为光源进行了脉冲宽度的测试.最高工作频率为：1 MHz,时间分辨率为：1.8 ps.     

半导体激光激发荧光粉转换白光照明系统设计

单管蓝光半导体激光器功率相对较低,为了获得高功率激光,利用多单管光纤耦合技术实现10 W蓝光激光输出,输出的激光激发荧光粉片合成的白光光源作为汽车远光灯光源。根据汽车照明法规要求设计了汽车远光灯照明系统并详述了抛物面反光罩、双凹透镜和荧光粉片的光学结构及对反光罩曲线参数、双凹透镜和荧光粉片的放置位置对光源色温均匀性及照度的影响。模拟设计了顶端19 mm×31.6 mm椭圆形开孔、底部直径5 mm圆形开孔、高60 mm的椭圆抛物面反光罩,荧光粉片置于距反光罩底部15 mm处时,在距光源25 m处的接收面上得到了5 m×12 m的椭圆光斑,白光光源的光通量为1 025 lm,中心色温为5 880 K,中心色坐标为(x=0.322 6,y=0.369 2),该汽车远光灯照明系统满足汽车照明法规要求。     

Effect of laser beam incidence angle on the thermoelastic generation in semi-transparent materials

When a laser beam is absorbed in a semi-transparent material, a volume acoustic source is created owing to penetration of the laser beam inside the material and to thermoelastic transduction. Many experimental and theoretical studies have been conducted to better understand this ultrasound generation process with normal laser light incidence on the material surface. The purpose of this paper is to analyze the effects of the asymmetry caused by oblique incidence of a laser line source on the generation of acoustic waves in semi-transparent isotropic materials. Experiments on a glass plate demonstrate that such an obliquely incident laser light strongly affects bulk acoustic waves generation. Compressional and shear waves are enhanced and the loss of symmetry of the acoustic source causes asymmetrical behavior of the acoustic waves. Surprisingly, compressional-wave amplitude decreases whereas shear-wave amplitude increases in the region where the electromagnetic energy is refracted. This feature is explained by semi-analytical calculations.