位相光栅衍射的矢量解法

采用矢量理论处理了多台阶位相光栅的衍射问题，用半数值的方法把微分方程转化成广义本征方程。在利用纵向边值关系作模式匹配时，引入了模式变换阵，反射系数阵和透射系数阵，从而获得了计算电磁场振幅系数阵的递推公式，最后求出任意偏振状态下各级透波和反射波的衍射效率。     

光盘多信道存贮分光技术

本文对光盘存贮技术中应用的多频声光和衍射光栅分光技术进行了分析、研究.并以二元计算全息理论为基础,用脉位调制技术通过计算机模拟,获得了产生均匀多光束衍射的位相光栅的精确周期结构参数.据此,研制了总衍射效率为73%,最大残余偏差为17.5%能满足实用要求的九光点均匀衍射位相光栅.     

透射衍射光栅内全反射级次

当前高功率激光装置系统中, 国内使用透射式衍射光栅进行光束采样, 国外甚至使用光栅聚焦并同时结合谐波分离和采样功能. 高功率激光辐照下, 除了0级透射打靶光以及目标取样光外, 其他级次衍射光的影响也不可忽视, 可能造成诸如鬼像聚焦破坏、时间脉宽测量不稳定、近远场测量噪声等问题. 尤其是透射衍射光栅内部全反射级次会导致光栅出射一系列规律的衍射花样, 造成上述干扰和危害. 首先理论上针对透射式光栅(包括取样光栅和聚焦光栅)进行了相应的计算和分析, 然后从实验上观察并测量了取样光栅内部全反射级次的现象, 并且结合镀减反膜前后的衍射现象进行了讨论, 最后分析并给出了如何消除或规避全反射级次和其他冗余级次影响的方法.     

软X射线位相型金透射光栅的设计与制作

根据衍射光栅的标量理论,计算并讨论了金透射光栅在软X波段衍射效率对光栅厚度和占宽比的依赖关系.结果表明,选择合适的光栅槽深和占宽比,高达 21.9%的衍射效率可能被获得,远高于振幅型光栅的+1级衍射效率10.14%.通过全息光刻与电镀转移技术制作的位相型金透射光栅由300nm的聚酰亚胺薄膜支撑,光栅槽深200nm,占宽比为0.55,周期为1μm,面积为20mm×5mm.在国家同步辐射装置上,测得其+1级透射衍射效率在波长λ=7.425nm时获得最大值,约为16%. 关键词： 透射位相光栅 全息光刻 电镀     

用CMOS线阵图像传感器测量透明材料的折射率

将衍射光栅干涉和CMOS线阵图像传感器技术相结合,提出了自动测量透明材料折射率的方法.介绍了用CMOS线阵图像传感器来实现透明材料折射率测量的基本原理和数据采集方法.采用曲线拟合计算条纹移动距离,提高了对干涉条纹移动量测量的准确性,折射率精度可提高到10-5数量级.     

基于Talbot效应的掺镁铌酸锂二维六角位相阵列光栅的研究

本文系统研究了基于泰伯效应(Talbot) 的位相可调掺镁铌酸锂二维六角位相阵列光栅及其光衍射成像, 对光栅占空比D、不同位相差Δφ、及泰伯分数β条件下的光栅近场光衍射强度分布进行了理论研究, 结果表明当光栅占空比D=52%、位相差Δφ=0.75 π、 泰伯分数β=0.2时, 光栅近场衍射光图像效果最佳. 实验设计与 制备了掺镁铌酸锂二维六角位相阵列光栅, 并对其进行了Talbot衍射光成像实验研究, 得到了不同位相差和不同泰伯分数β条件下光栅近场衍射 光图像, 实验结果与理论研究结果相符. 关键词： 二维六角位相阵列光栅 掺镁铌酸锂晶体 泰伯效应     

位相光栅色散特性的矢量衍射理论分析

在矢量衍射理论基础上给出了适用于任意斜入射下位相光栅反射区和透射区的广义光栅方程和广义色散公式，对位相光栅色散能力做了理论和数值分析，考察了入射角、入射方位角、入射波长、光栅周期、衍射区域介质折射率和衍射级次等六个物理量之间的相互制约关系，确立了光栅约束不等式，指出了提高光栅色散的所有可能的途径. 关键词： 位相光栅 色散特性 矢量衍射理论     

凹面光栅衍射效率的研究进展

凹面光栅因同时具有聚焦和色散功能而广泛应用于各类紫外、可见和红外波段的光谱分析仪器中,尤其是平场凹面光栅可以结合线阵或面阵探测器来实现即时分析。凹面光栅衍射效率的高低直接影响光谱仪器的信噪比和信号采集,其相关研究也逐渐为人们所关注。介绍了凹面光栅衍射效率的研究进展,比较了由机械刻划法和全息法制作的凹面光栅在掠入射下衍射效率的差别,分析了现有计算衍射效率方法的优缺点,并且对凹面光栅衍射效率的研究趋势做了简要预测,提出了需要同时在凹面光栅的主截面和非主截面内考虑光束对其衍射效率的影响。     

二,三及五等分激光分束器的设计与制作

由于激光分束器在光互连系统、光盘及光多路输出系统中有广泛的应用．而用二元位相光栅制做的激光分束器不仅体积小，且使用方便，灵活耐用．因此有诱人的发展前景．我们设计二元位相光栅激光分束器的方法是从二元位相光栅复振幅透过率的一般公式出发，经过付里叶积分可得到各级衍射光的强度公式，从而列出各级强度相等并取得极大值条件的方程，再利用数值计算方法求解．这种方法不仅物理意义明确，也达到了最优化设计的结果，是目前解决这一问题的最简便有效的方法．1设计二、三及五等分激光分束器的原理对于轮廓函数为矩形的一维二元位相…     

一种基于CCD的实时测量光栅常数的方法

光栅常数是检验光栅质量的重要参数之一.该文介绍了一种实时检测光栅参数的方法,即利用面阵CCD采集光栅衍射图像信息,通过计算衍射±1级光斑与主极大光斑的能量比得出光栅常数.这种方法具有检测速度快、系统简单、精度高等特点,可用于生产线上光栅的实时检测.     

多层介质膜脉宽压缩光栅的严格矢量分析

用于展宽和压缩激光脉冲的多层膜脉宽压缩光栅是由多层介质高反膜和位于其顶层的浮雕光栅构成。以设计的高反射多层膜为基础,利用傅里叶模式理论分析了其衍射场分布,给出了TE波自准直角入射的使用条件下,多层介质膜脉宽压缩光栅衍射效率的表达式。以-1级衍射效率为评价函数,分别讨论了HfO2和SiO2为顶层材料时,多层膜脉宽压缩光栅-1级衍射效率高于0.95的光栅结构参量范围。结果表明,在该条件下,选择HfO2为顶层材料时,光栅结构参量有较大的取值范围。给出了优化的光栅结构参量,并分析了光栅制作误差及其使用条件的宽容度,对光栅制作工艺和使用具有一定的指导意义。     

紫外光诱导液晶相位光栅

使用紫外光诱导取向技术制作了可转换的液晶相位光栅,通过光掩模两次曝光的方法形成光栅条纹.这种光栅制作工艺较为简单,不需要上下基板精确的对准,驱动电压较低.采用He-Ne激光器和光探测器进行测试,结果表明,衍射效率具有电场调制性并出现同预测一致的衍射条纹.对液晶光栅的偏振特性进行了研究,利用琼斯矩阵和衍射理论对液晶相位光栅衍射强度进行了分析和模拟计算.     

亚波长光栅的偏振闪耀特性

 使用琼斯矩阵的方法推导了连续结构亚波长光栅的衍射方程,给出了光栅衍射效率表达式,对偏振特性与衍射特性进行了研究。发现连续结构亚波长光栅仅存在３个衍射级,总衍射效率为100%,且衍射效率可在衍射级间任意分配,0级的偏振态与入射光的偏振态相同,±1级衍射光偏振态与入射光无关,－1级为左旋圆偏振光,＋1级为右旋圆偏振光。通过设置入射光偏振态与光栅相位延迟等参数,可使光栅具有闪耀特性,据此可用于设计高效偏振光分束器和偏振光开关。     

Zero infrared reflectance anomaly in doped silicon lamellar gratings. I. From antireflection to total absorption

Zero-reflectance phenomenon for a binary lamellar grating on n-Si substrate irradiated by normally incident TE polarized plane electromagnetic wave of wavelength 10.6 μm is studied. The treatment is performed in the strong diffraction regime, where the structural dimensions and the wavelength are of the same order of magnitude, using data on the IR dielectric function of bulk doped silicon and a version of rigorous coupled-wave analysis. The evolution of normal reflectance zeros with increasing electron concentration from dielecric to metallic-like n-Si is traced. It is shown that the groove height undergoes sharp increase and the period shrinks when plasma wavelength becomes equal to the radiation wavelength. This marks the transition from the antireflection to the total absorption regime where most of incident power is absorbed in the grating region. The cavity-resonance origin of total absorption and satellite peaks in the spectral response are discussed.     

Laterally deformable nanomechanical zeroth-order gratings: anomalous diffraction studied by rigorous coupled-wave analysis

We describe a novel optomechanical device that produces strong reflectance and polarization modulation of incident light. The structure is based on a suspended nanomechanical grating with lateral deformability, and rigorous coupled-wave analysis has been used to fully model the optical properties of the device. The grating consists of two interdigitated gratings that may be moved with respect to each other with an applied force. The structures proposed here are designed to be readily manufacturable with device processing developed for surface-micromachined microelectromechanical systems and with known microelectromechanical systems materials, such as silicon, silicon nitride, and amorphous diamond. As the spacing of the grating is changed, an anomalous diffraction effect is observed, a Wood's type anomaly in which there exists a resonance in propagating leaky modes within the grating, resulting in a dramatic change in the reflectance characteristics for slight changes in the grating. One of the unique features of this structure is that a reflected optical signal can be used to detect subangstrom in-plane motion of structures greater than 10 nm.     

湿法和溶脱法的亚微米ZnO:Al光栅制备

以激光干涉法得到的光刻胶图案为掩模,采用湿法刻蚀和溶脱-剥离法制备了具有良好减反射特性的亚微米掺铝氧化锌（ZnO:Al, AZO）光栅。表面形貌特征和反射光谱测试结果表明,湿法刻蚀较溶脱-剥离法得到的AZO光栅表面更为粗糙,两者均方根粗糙度分别为25.4,7.6 nm。在400～900 nm波段,两种方法制备的周期和高度相同的光栅,平均总反射率分别由AZO薄膜的12.5%下降到8.3%和10.2%。两者的平均镜面反射率分别为6.2%和6.6%,平均漫反射率分别为2.1%和3.6%。湿法刻蚀得到的表面较为粗糙AZO光栅的漫反射明显减弱,从而导致总的减反特性优于溶脱-剥离法得到的表面起伏相对较小的AZO光栅。     

Analysis on diffraction properties of the transmission phase grating

Diffraction properties of the transmission phase grating are analyzed in terms of the Fourier optics theory. The analysis results show that the diffraction intensity distribution of the transmission phase grating is closely related to the optical thickness of the grating and the wavelength of the incident light, and not only determined by the grating's period and slit width. For monochromatic incident light, more than 80% of the diffraction energy will concentrate to the first diffraction order under certain conditions. For white incident light, the energy of the first order of diffraction spectrum may be much higher than other orders. Based on these results, some possible applications of the transmission phase grating are discussed.     

真空紫外波段光栅二级衍射效率测量装置

利用光栅二级衍射会影响反射样品光谱反射率结果的原理,通过计算不同光谱反射率获得了光栅二级衍射效率。介绍了测量二级衍射效率的实验装置,该装置采用双光路单色仪结构,使用已知光谱辐亮度氘灯作为光源,探测器为光电倍增管,通过水杨酸钠膜将紫外光转为可见光。以波长161nm为例,测量了5块反射镜样片,计算得到光栅二级衍射效率为0.00611×(1±0.0777)。分析表明,该方法采用的测试装置简单,系统不确定度为14.08%,可以实现真空紫外波段光栅二级光谱衍射效率的连续测量。     

Theory of laser-induced amplitude and phase gratings including photoselection,orientational relaxation and population kinetics

The generation of amplitude and phase gratings in an absorbing medium is discussed, including the effects of light polarization, population kinetics and orientational relaxation. A theory is given which describes light diffraction by a combination of an amplitude and a phase grating. It is shown that the coherent coupling effect in transient absorption measurements is solely due to the amplitude grating. Weak absorption and a low triplet yield favour diffraction of the probing beam by the phase grating in triple-beam experiments. Phase grating experiments can be performed with highly soluble absorber dyes, the absorption maximum of which is far away from the laser wavelength. Due to photoselection, diffraction by an amplitude grating depends on the polarization of the probing beam while phase grating diffraction is insensitive to this. Perpendicular polarization of the two exciting pulses prevents the buildup of a phase grating and results in light diffracted by the amplitude grating that is proportional to the transient dichroism signal as known from the common absorption relaxation.