液晶空间光调制器的调制特性测量

分析了液晶空间光调制器LC2002的工作原理,测量了振幅调制特性和最佳相位调制特性曲线.对经扭曲向列液晶空间光调制后的待测波面进行横向剪切干涉,用CCD记录其干涉图样,采用一维图像分析法得到最大相位调制为0.837π.实验证明液晶空间光调制器可以很好地进行相位调制.     

利用相关分析法测量空间光调制器的相位调制特性

基于一维干涉条纹图像的相关分析法可实现液晶空间光调制器相位调制特性的测试。给出了XGA2L11型电寻址液晶空间光调制器的相位现场测试原理、测试装置和测试步骤。利用范德卢格特型光电混合相关器对测试结果进行了实验验证。结果表明,该方法具有原理简单、适应性强和精度高等优点。     

液晶空间光调制器相位调制测量及波前校正

提供了一种简单且精度较好的测量液晶空间光调制器相位调制特性的方法,即相位与电压(灰度)之间的关系。采用数字波面移相干涉仪,由干涉仪直接给出不同灰度对应的相位差,从而得到液晶空间光调制器的相位调制曲线。利用液晶空间光调制器实现了波前校正。由干涉仪作波前测试,对待校正的畸变波前进行泽尼克多项式描述,根据液晶空间光调制器的相位与灰度的关系,产生相应的灰度图,获得畸变波前的共轭波前,从而完成静态波前的校正,使相关参数如PV值、RMS值和Strehl比值得到了改善。     

平行排列液晶器件的波前调制特性

设计了一种新型的平行排列液晶相位调制器(LC PM)，可在纯相位的模式下进行相位调制，研究了液晶相位调制器的光学特性，理论上给予了分析．对畸变波前进行了调制，在1 cm2的校正面积上，调制后的准确度PV(peak to valley)值接近λ／15(λ=0.6328 μm)，RMS(Root Means Square)可达到λ／100，斯特列尔比SR (Strehl Ratio)达到0.989．改变了传统的扭曲向列液晶器件难于进行纯相位调制和得到高准确度调制的缺点，达到了理想的效果.     

空间光调制器振幅和相位调制特性的实验研究

本文实验研究了德国Holoeye Photonics AG公司生产的反射型电寻址液晶空间光调制器LCR1080的振幅和相位调制特性。在传统的振幅调制测量方法中引入最佳起偏角的测定,利用直接测量法获得了该空间光调制器精确的振幅调制特性曲线。采用双缝干涉法对空间光调制器的相位调制特性进行了测量,有效地克服了泰曼-格林干涉等方法受环境因素影响较大的缺点。通过改变加载到空间光调制器图像的灰度值,获取其相位延迟与灰度值的非线性关系。这些研究对基于液晶空间光调制器的光信息处理、自适应光学等研究奠定了良好的实验基础。     

高精度纯相位液晶空间光调制器的研究

研制了平行排列液晶空间光调制器（LC SLM）。论述了平行排列液晶相位调制的理论,进行了计算模拟。对液晶空间光调制器相位调制特性和振幅调制特性进行了测量,实验结果表明,在整个灰度级范围内是纯相位调制的空间光调制器,并且调制的范围可达到0．6λ。在ZYGO菲佐干涉仪上进行了精度特性的研究,得到了非常好的结果,在1cm^2的面积上,进行了畸变波前的调制,其精度峰谷值可达0．098λ,均方根值可达0．017λ。在此精度的基础上产生了π相位差的栅结构,证明了这种液晶空间光调制器可以很好的进行相位调制。     

基于液晶空间光调制器的脉冲整形系统校准及应用

搭建了反射式光脉冲整形系统,通过改变加载到液晶空间光调制器各像素点的调制电压,测定系统分辨率及调制电压与输出信号光强和相位变化的关系,并对液晶空间光调制器进行校准.实验结果表明:光强随调制电压周期变化,相位随调制电压非线性变化;系统分辨率为10GHz,像素调制间隔为0.08nm,即能够实现对频率间隔10GHz的光信号的调制.应用该系统,以谱线间隔为10GHz的光学频率梳为信号源,对脉冲频谱进行整形,产生了平坦、高斯型、三角、倒三角及光学频率梳信号.     

基于多光子脉冲内干涉相位扫描法对飞秒激光脉冲进行相位测量和补偿的研究

研制了一套基于多光子脉冲内干涉相位扫描方法的可以同时对飞秒激光脉冲进行相位测量和补偿的实验系统装置.实验中,通过自主研发的LabVIEW程序控制液晶空间光调制器和光纤光谱仪,对待测飞秒激光脉冲施加相位扫描,并同时记录受到调制的飞秒激光脉冲的倍频光谱,得到了多光子脉冲内干涉相位扫描(MIIPS)轨迹图.通过MIIPS轨迹图的三次测量和迭代运算,还原出了经过预先啁啾调制的中心波长约为810 nm、重复频率为1 kHz的飞秒激光脉冲的光谱相位,测量精度在0.1 rad以内.根据测量结果,利用液晶空间光调制器对该飞秒激光脉冲进行相位补偿,得到了近似傅里叶变换极限的飞秒激光脉冲.这一装置将在多光子显微成像、脉冲整形、飞秒激光光谱学等众多领域发挥重要作用.     

在光学相关器中测试滤波空间光调制器的相位调制特性

研究了在范德卢格特型光电混合相关器中,利用朗奇光栅图像替代实物光栅测试滤波空间光调制器相位调制特性的原理和方法.对XGA2L11型空间光调制器的相位调制特性进行了现场测试,并对测试结果进行了误差分析和光学相关实验验证.结果表明,该方法不需要单独构建测量装置而是完全在相关器的工作状态下测试,保证了空间光调制器的特性测试结果和实际工作性能的一致性.     

液晶空间光调制器的混合场效应

通过研究透射光的偏振方向或者偏振状态研究了液晶空间光调制器的混合场效应.观测了不同条件下液晶空间光调制器的透射光的线偏度以及主轴方向,分析了扭曲向列效应和双折射效应的变化.实验结果表明:液晶的双折射效应叠加在扭曲向列效应上,共同影响透射光的状态,其综合效应即混合场效应是液晶空间光调制器的主要工作模式.     

Mueller-Stokes polarimetric characterization of transmissive liquid crystal spatial light modulator

In the twisted nematic liquid crystal spatial light modulators (TN-LCSLM), distortion of uniform twist and decrease in tilt angle of liquid crystal molecules on application of an electric field lead to amplitude and phase modulations of the transmitted or reflected wavefront, respectively. The amplitude and phase modulation characterization of TN-LCSLM using Jones calculi is simple and extensively used but does not give any information about important polarimetric parameters such as diattenuation and depolarizance. On the other hand, the characterization using Mueller calculi provides all information in terms of polarimetric properties such as diattenuation, retardance (birefringence) and depolarization. In this paper, polarimetric properties of the transmissive TN-LCSLM (HOLOEYE LC2002) are characterized measuring 17 different Mueller matrices at different addressed gray scale through Mueller Matrix Imaging Polarimeter (MMIP) at 530 nm wavelength. Lu-Chipman polar decomposition for Mueller matrix is utilized to separate out three independent Mueller matrices for diattenuation, depolarization and retardance as a function of addressed gray scale. Further, Mueller-Stokes combined formulation is used to examine the effect of depolarization present in the TN-LCSLM on six different states of polarization and evaluation of eigenpolarization states for the TN-LCSLM has been presented.     

High-efficiency reflection phase tunable metasurface at near-infrared frequencies

The realization of active modulation of reflection phase based on metasurfaces is of great significance for flexible control of electromagnetic wavefront, which makes metasurfaces have practical application values in polarization conversion, beam steering, metalens, etc. In this paper, a reflection phase tunable gap-surface plasmon(GSP) metasurface based on phase change materials Ge_2Sb_2Te_5(GST) is designed and experimentally demonstrated. By virtue of the characteristics of large permittivities difference before and after GST phase transition and the existence of stable intermediate states, the continuous modulation of near-infrared reflection phase larger than 200°has been realized. At the same time, through the reasonable design of the structure sizes, the reflection has been maintained at about 0.4 and basically does not change with the GST phase transition, which improved the working efficiency of the metasurface significantly. In addition, the coupled-mode theory(CMT) is introduced to make a full analysis of the modulation mechanism of the reflection phase,which proves that the phase transition of GST can induce the transition of metasurface working state from overcoupling mode to critical coupling mode. The improvement of the metasurface working efficiency has practical values for wavefront modulation.     

Numerical reconstruction of an infrared wavefront utilizing an optical phase modulation device

We utilize nitroanisole, that absorbs infrared (IR) radiation as heat, as an optical modulation device based on a thermal process. The nitroanisole exhibits a thermal lens effect, i.e. a temperature dependent refractive index. Hence, the nitroanisole can induce phase modulation to visible light, in direct response to intensity of the incident IR radiation. The proposed method can be used to obtain the phase modulation distribution that corresponds to the IR intensity distribution, i.e. the IR hologram itself, on the nitroanisole by examining the phase map of visible light that is modulated upon passing through the nitroanisole. The IR wavefront can be reconstructed by calculating extracted IR holograms through the Fresnel transform. It is verified that both the amplitude and the phase of the IR wavefront can be reconstructed accurately by proposed method.     

采用环路径向剪切干涉法测量液晶电视的相位调制特性

提出了一种测量液晶电视相位调制特性的新方法,并对液晶电视在该干涉仪中形成的条纹图进行了解释,对EPSONP13VM125液晶电视的相位调制特性进行了实际测量,结果表明该测试方法能实现液晶电视相位调制特性的全场、快速和准确测量.     

K-F系统中的波前相位调制与光强调制的转换

研究在由一薄片Ｋｅｒｒ 介质与一块二维反馈镜组成的非线性光学系统中光波前相位与光强的转换过程。根据基尔霍夫衍射定理,导出了单一模式以及小畸变近似条件下多个模式的相位－ 光强转换关系的方程。结果证明：通过衍射,入射波前相位各阶Ｚｅｒｎｉｋｅ 模式成分的大小转换为反馈光光强的非线性调制。     

二元纯位相片实现半导体激光器到单模光纤的耦合

采用二元光学位相调制的基本思想，用二元纯位相型光学系统将椭圆高斯型激光束与单模光了佳耦合。采用两块纯 位相片来进行波前变换，将椭圆型高斯激光束转变成对称圆高斯激光束，并与单我纤的基模最佳匹配耦合。     

近红外瞬态脉冲波前高精度干涉检测技术

惯性约束聚变(ICF)系统中高能瞬态脉冲激光由于脉冲时间短、能量高、波前畸变大,通常的检测方法难于检测脉冲激光波前。提出了一种基于空间相位调制技术可用于近红外瞬态波前高精度检测的环形径向剪切干涉仪。该系统可以以30~150 mm的圆瞳和方瞳口径、对波长为1064 nm的近红外纳秒级脉宽的脉冲激光波前实现共路、无参考面的瞬态、高精度的检测。系统的波前重构理论经过计算机仿真验证,精度达1/1000λ以上;检测结果与ZYGO数字波面干涉仪进行了比对,峰谷值、均方根值均优于1/15λ,并具有很好的可重复性。该系统目前已用于惯性约束聚变系统的脉冲检测,并且该技术适用于各种可见光和红外波段激光。     

Sine-azimuthal wavefront-modulated cosh-Gaussian beams with half-space amplitude modulation

Half-space amplitude modulation was introduced into the linearly polarized cosh-Gaussian beams with sine-azimuthal variation wavefront, and corresponding tunable focal patterns were investigated in detail. Simulation results show that focal pattern can be changed remarkably by the amplitude modulation. And under condition of different beam parameters and phase parameter that indicates the sine-azimuthal variation wavefront, the focal pattern evolution also differs considerably. Some novel focal shape may appear, including cross-shape, multiple-peak focal pattern, multiple intensity lines, wheel focal pattern, bell shape, and swallowtail focal spots. Symmetry of the whole focal pattern can be altered remarkably, the whole focal pattern evolves into uniaxial symmetry about perpendicular axes for odd and even phase parameter, respectively.     

采用空间—角度复用的盘式三维全息存储

提出基于空间－角度复用技术的盘式三维全息存储方案，给出这一技术的基本原理，并采用简化的光线分析方法对该方案的可行性进行分析。研究表明，这是一种能提供高密度和高数据传输率，而读写系统又相对简单的盘式三维全息存储方案，具有潜在的应用前景。