Use of the Advanced Photon Source and Center for Nanoscale Materials, Office of Science User Facilities operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. We acknowledge Dr. Han Wen, NHLBI / National Institutes of Health, Bethesda, MD 20892, USA, for many helpful suggestions during the data processing.

1.实验计划<ol><li>确定同步加速器光束线。与束线科学家找到实验在该束线的适当性。 注:本稿件报道实验是在1 BM-B光束线，这是致力于光学和探测器的检测，APS的XSD下进行。 </li><li>提交用户的建议和梁的请求。 </li><li>制定出实验的细节与束线科学家和指定所需的仪器，包括用于光栅和检测器对齐，二维检测器（CCD或CMOS），覆盖所述检测器之间所需要的最小和最远的距离长平移台电动平台相位光栅。 </li><li>按照在相关网站提供的说明制备用于光束的时间。完成安全培训和必要的实验安全性评估的形式。 </li></ol> 2.二维棋盘博士的制备ASE光栅<ol><li>确定光栅， 对 ，这是关系到干涉图案， 对θ的期间，沿不同宽度方向角θ的周期。可见性值，Vθ（d）中 ，沿不同θ角的干涉的振荡作为光栅到检测器的距离的函数，D。 在距离的2-D棋盘π/ 2的相位光栅，Vθ（ 四 ）的峰， <img alt="式（1）" src="/files/ftp_upload/53025/53025eq1.jpg" /> 其中n = 1，2，3 ...，λ的光子波长。干涉图案具有p个θ= P /√2沿着正方形块的对角方向和一个周期p 的θ=π/ 2沿正方形块的边缘的特征周期。 P的选择，因此，依赖于以下标准。 </li><li>请确保至少有几Vθ（D）的峰值是最大光栅到探测器距离内，或实验站的空间限制，D 最大 。为了满足D N，θ&lt;D 最大 ，它遵循 <img alt="公式（2）" src="/files/ftp_upload/53025/53025eq2.jpg" /> 对于n = 5，D 最大 =1μm时，λ= 0.06888纳米（18千电子伏），它赋予pθ&lt;3.9微米。 </li><li> D中最大 ，确保在最大距离D N在Vθ（ 四 ）峰的高度，θ小于那头Vθ（ 四 ）在d 1峰值的系数γ，θ以有一个准确的高斯衰减函数拟合。因此，γ= Vθ，N（D）/Vθ，如图1（d），它是第 n 个峰的可视性于第一峰的比值。对于在用相干长度高斯强度分布的X射线源，ξθ，一π/ 2的相位光栅需要的期间，以满足 <img alt="公式3" src="/files/ftp_upload/53025/53025eq3.jpg" /> 例如，用γ= 10％，ξθ= 5微米及以上的参数，它赋予pθ&gt; 2.4微米。 </li><li>确保该干涉图案， 对θ，的周期是通过选择正确的检测器系统比检测器的空间分辨率大几倍。 </li><li>确定的厚度，T为，φ相移所需的光栅，在X射线光子波长λ，使用 <img alt="公式4" src="/files/ftp_upload/53025/53025eq4.jpg" /> 其中δ是相移材料的折射率递减。例如，对于金的折射率递减是9.7×10 18千电子伏-6。非盟厚度φ=π/ 2相位光栅因此是1.8微米。 </li><li>制造的相位通过电镀金成图案化聚合物模具上的氮化硅光栅（ 的 Si 3 N 4）的窗口。 注:制备氮化硅（Si 3 N 4）窗基板和制造中的光栅结构的方法如下。 <ol><li>通过首先释放的 Si 3 N 4膜以形成X射线透明窗准备基板。 </li><li>获得具有低应力（&lt;250兆帕） 的 Si 3 N 4沉积在从一个供应商提供的晶片的两侧硅（Si）晶片。 </li><li>装载晶片到磁控溅射淀积系统淀积Cr和Au充当电镀基。 </li><li>铬次的存款5纳米烯在晶片的一侧上的Au为30nm，按照生产商的指示。 注:从系统制造商的沉积过程将包括诸如沉积速率的信息。 </li><li>卸载从沉积工具晶圆。使用沉积有Cr和Au为光栅制造晶片的侧面。 </li><li>确定光栅的总大小，然后设计一个光刻掩模图案膜稍大。使用设计通过从供应商处购买来获取光刻掩模或制造的光刻掩模。 </li><li>关于在没有Cr和Au涂层的晶片的背面侧旋光致抗蚀剂的3微米厚的一层。暴露利用设计光刻掩模用紫外线光刻工具的抗蚀剂20秒。显影曝光在含水碱性显影剂溶液抗蚀30秒，然后用去离子水淋洗并干燥用流动的 N 2。 </li><li>装载晶片进入活性离子蚀刻（RIE）工具瓦特第i个图案化光致抗蚀剂所面临的腔室。使用CF 4的等离子体来蚀刻暴露的 Si 3 N 4以下工具的指令。 </li><li>疏散蚀刻室和输入蚀刻配方为RIE工具。运行配方直到在Si 3 N 4层被完全蚀刻和Si层在图案曝光。 </li><li>通过浸没入约8小时30％的KOH溶液中加热至80℃蚀刻在晶片背面露出的Si。蚀刻速率是大约使用所述配方为75μm/小时。 </li><li>硅蚀刻完成后，用去离子水冲洗和干燥用流动的 N 2。样品是准备光栅制造。 </li></ol></li><li>制造用于相使用以下步骤光栅电镀模具。 <ol><li>设计方棋盘光栅图案与补偿模式由100-250纳米的减少暴露的方形图案大小偏置。包括围绕GRAT一个&gt; 50微米的宽边框ING模式的厚度确认以后的进程。 </li><li>加载样品放入抗蚀旋涂器和沉积聚（甲基丙烯酸甲酯）（PMMA）正型抗蚀剂在样品的光栅侧的解决方案。运行抗蚀剂旋涂机，以形成2〜3.5微米的取决于期望的最终光栅厚度厚的抗蚀膜。 注:对纺丝速度与膜厚度信息自旋曲线由聚甲基丙烯酸甲酯溶液供应商提供或可凭经验确定。 </li><li>装载晶片到100千电子伏的电子束光刻系统。 </li><li>用大电流接触超过10 nA的更大的校准曝光的工具。 </li><li>露出用100千电子伏的电子束光刻工具来创建光栅图形，其中曝光区域将在显影工序中除去的PMMA抗蚀剂。根据抗蚀剂厚度使用的1,100-1,250μC/ cm 2的曝光剂量范围。 </li><li>卸载从工具的样本。 </li><li>发展曝光的光刻胶通过在7浸没:3（体积）异丙醇（IPA）:30-40秒，轻轻旋转去离子水的溶液。用IPA冲洗，然后用流动的 N 2干燥。确保聚甲基丙烯酸甲酯，通过用光学显微镜观察露出面积充分的发展。 </li><li>加载样品与朝向腔室的PMMA图案的RIE工具。 </li><li>疏散蚀刻室和输入除渣蚀刻配方到RIE工具。该除渣工艺是短（&lt;30秒），O 2等离子蚀刻基础，从暴露的光栅区域除去残留的PMMA。 </li></ol></li><li>通过电镀成使用以下步骤的制造模具完成的Au光栅。 <ol><li>通过扫描轮廓的探头横跨包括了厚度确认帧确保电镀模具厚度。 </li><li>淹没样品进入该Au-亚硫酸盐电镀液加热到40℃。电镀的设置是由充满ELE烧杯ctroplating溶液，以恒定电流DC电源，和一个铂网状阳极。 </li><li>通过在曝光图案计算的露出的Au确定样品的电镀区域，然后计算出所需的电流密度，这是用于设置沉积速率主可变电流。 </li><li>计算电镀时间使用由施加的电流密度确定的镀覆速率，以达到所需的光栅厚度。 </li><li>打开直流电源施加在样品上所确定的当前，作为阴极和板为大约一半的总镀覆时间。 </li><li>测量使用在步骤2.8.1中使用的方法相同的方法的电镀厚度。 </li><li>打开直流电源到电镀金入PMMA模具和电镀到所需的光栅厚度，考虑到在步骤2.8.6测定的镀高度。 </li></ol></li><li>通过浸入样品中取出用温水溶剂中的聚合物模具。然后用光学检查升显微镜和扫描电子显微镜（SEM）确认光栅周期，占空比和光栅厚度。 注意:有两台2-D棋盘相位光栅（一个用于实验，一个作为备用）准备好了，过几天在实验开始前。 </li></ol> 3.实验设置和校正的同步加速器设施<ol><li>要求束线科学家到X射线束的能量或波长设置为所需的值相匹配的相位光栅。在APS 1-BM光束线经常使用X射线能量是6和28千电子伏之间。在这种情况下，调光子能量至18千电子伏。 </li><li>选择用于检测器系统所需要的物镜。在这里，使用Coolsnap HQ2 CCD探测器，具有6.45×6.45微米2的像素尺寸的1392×1,040像素的成像。要解决最小的干涉图案，使用EC计划NEOFLUAR 10×目标。检测器系统的有效像素尺寸包括放大微观目标的效果是这样0.64微米。所估计的空间分辨率为约2微米，这主要是由于在检测器系统的点扩散函数。 </li><li>设置粗糙聚焦检测器系统的，将闪烁器（镥钇oxyorthosilicate，150微米厚）在从透镜的"工作距离"（〜5.2毫米用于所使用的系统）。首先，通过监控下的"连续模式"为闪烁位置获得的图像是使用微微电动调节设置在环境光的聚焦。 </li><li>移动的2-D检测器进入X射线束，利用垂直和水平阶段对齐检测器的光束中心的中心。 </li><li>放置一个&#39;相样本"，例如一块泡沫塑料，进入X射线束。执行精细通过观察从相位样本的散射图案和调节该闪烁体的位置，直到最高的图像清晰度聚焦在检测器系统的。 </li> &lt;/ OL&gt; 4.执行一致性测量<ol><li>放置2维棋盘光栅进入X射线束，其中的光束的相干性是被测定。在这种情况下，它是在从弯曲磁体源34米。 </li><li>调整的2-D棋盘相位光栅垂直于X射线束传播方向的平面。 </li><li>通过使用电动平台和观察下检测器连续模式获取的图像居中光栅的X射线束。 </li><li>绕在X射线束传播方向（y），以使棋盘图案的对角线方向是沿着所需横梁方向上的光栅。在这种情况下，对齐棋盘中的光束的水平和垂直方向的对角方向（优选的测量方向）。微调其它两个轴（x和z）内的光栅的旋转，以确保其垂直于X射线光束，这是通过最大化在水平和垂直两个方向上的干涉周期来实现的。 </li><li>将尽可能接近实际可能的相位沿着光束传播方向光栅探测器系统。在这项研究中，使用43毫米的距离。 </li><li>计算干涉图案的最小周期。该π/ 2棋盘具有周期p光栅= 4.8微米会分别产生与对θ的干涉图案=沿对角线与棋盘图案的非对角方向3.4微米和pθ= 2.4微米（最小周期）。估计需要在两者之间由公式鉴于第五θ（D）峰值位置（1），得到一个平滑的曲线的数据点的数量。 </li><li>选择合适的曝光时间为每个干涉图，在这种情况下，四秒钟。 </li><li>用相同的曝光时间（ 例如 ，4秒）在记录干涉图不同的光栅到检测器的距离。选择基于所述光束的强度级的曝光时间。从最小光栅到检测器的距离（43 MM）开始，移动由小间隔的X射线的下游检测器（测定10毫米根据步骤4.6）和记录在每个检测器的位置的干涉直到最大可能grating-到检测器的距离（750毫米）。 </li><li>获得具有相同的曝光时间（4秒）暗帧图像，但关闭X射线束，并保持所有其他实验条件相同。 </li></ol> 5.数据分析注:目前可用于数据分析没有标准的软件。 <ol><li>使用选定的图像处理程序，读出的暗帧图像（S）和数据映像中。减去（平均）暗帧图像校正数据镜像。 </li><li>傅立叶变换暗帧校正图像，从而产生可见谐波峰值在水平（52 = 0°），垂直（θ= 90°），以及θ= 45°，θ= 135°的方向。 </li><li>产量为0 级峰值为中心的0 阶谐波图像。图像的长度和宽度分别等于0 级和沿水平和垂直方向1 次顺序峰之间的距离。同样地，获得的沿横向方向的相同的长度和宽度的1 次高次谐波的图像。 </li><li>傅立叶逆变换（IFT）裁剪的谐波图像。从第1 次的IFT图像的振幅的平均值的比率沿任何横向方向上，从第 0次谐波图象的IFT图像的次谐波图像给出沿该方向的可见性。 注意，此过程是有效的，如果所测量的干涉存在少数的高频分量。否则，可以使用的CORRE傅立叶应的谐振峰强度从5.4步，而不是变换的图像。由于光束的发散，谐波峰值位置将在不同的光栅到检测器的距离逐渐变化。因此，修正为p&#39;在每个距离θ或需要一个峰发现过程。 </li><li>在不同的光栅到检测器的距离的所有所测量的图像重复步骤5.1-5.4和保存各图像的可见度值。 </li><li>绘制能见度Vθ（d）作为光栅到检测器的距离的函数。在Vθ（ 四 ）的峰确定的数据点。需要注意的是完整的曲线，测定只是为了更好地确定由公式（1）给定的峰值位置。每个峰的两侧手动选择峰值数据点以及相邻的数据点。 </li><li>绘制高斯拟合函数为所选数据点。提取标准偏差，σθ，日的Ë高斯函数拟合。 </li><li>获得横向相干长度，ξθ，用 <img alt="公式5" src="/files/ftp_upload/53025/53025eq5.jpg" /></li></ol>

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</ol>

The authors have nothing to disclose.

图5示出沿所有四个方向的估计横向相干长度。显然，90°的方向上具有较高的ξ相对于0°方向θ。由于束线光学对在光栅的相对位置的光束相干性的影响可以忽略，所测量的相干区域是成反比的源尺寸的区域。所呈现的X射线束相干测量技术准确映射这可以示出为沿垂直方向（参照图5）其长轴的椭圆。要注意的是与周围的自成像距离的自成像距离或几?...

第三代硬X射线同步辐射光源，如ANL，莱蒙特，IL，USA（http://www.aps.anl.gov）的APS，都对X射线科学的发展影响巨大。的同步加速器辐射源产生的电磁辐射的光谱，从红外线到的X射线的波长，当带电粒子，例如电子，是由以光速附近移动中的圆形轨道。这些来源具有非常独特的性能，如高亮度，脉冲和皮秒定时结构，以及大的空间和时间相干性。 X射线束的空间相干性是在第三和第四代同步源的一个重要参数和实验利用这个特性，在过去的二十年1急剧增加的数量。这些来源，如计划多弯曲消色差透镜（MBA）的晶格为APS储存环的未来的升级，将显着增加光束相干通量（HTTP://www.aps.anl.gov/Upgrade/）。的X射线束可使用一个晶体单色实现更高的时间相干性来调节。的同步加速器源的横向相干性比的，因为从源到实验站的低的电子束发射度和长传播距离的基于实验室X射线源显著更高。 通常情况下，杨氏双针孔或双缝实验用于通过干涉条纹2的可见性的检查来测量光束的空间相干性。以获得完整的复相干函数（CCF），需要与放置在与各分离，这一点，特别是对于硬X射线，麻烦和不实际的不同位置上的两个狭缝系统测量。均匀冗余阵列（URA）也可以通过使用它作为移相掩模3被用于光束相干性的测量。虽然该技术可以提供完整的CCF，它不是无模型。最近，基于Talbot效应干涉测量技术使用周期性对象的自成像特性被开发。这些干涉仪利用在光栅下游获得梁横向连贯性4-9一些自成像距离测量的干涉知名度。使用两个光栅系统横向连贯性的测量也有报道7。 映射横梁一致性，沿垂直和水平方向同时首先由日本特Guigay 等报道5。最近，科学家在光学组，X射线科学部（XSD），APS的报告两个新技术测量光束沿两个以上方向上同时使用两种方法横梁连贯性:一个具有棋盘相位光栅8，另具有圆形相位光栅9。 本文中的测量电键相和数据分析程序用于获得光束的横向相干沿0°，45°，90°，和135°方向相对于水平方向，同时说明。测量在APS的1-BM束线进行与棋盘π/ 2的相位光栅。在协议部分中列出这项技术的细节包括:1）实验规划; 2）制备的2-D棋盘相位光栅; 3）实验的设置和调整的同步加速器设施; 4）进行一致性测试; 5）数据分析。另外，代表性的结果示来说明该技术。这些程序可以在与光栅图案的最小变化许多同步加速器束线进行。

<table><tbody><tr><td>1-BM-B bending magnet X-ray source</td><td>Advanced photon Source/ Argonne National Lab</td><td></td><td>&lt;a href=&quot;http://www.aps.anl.gov/Xray_Science_Division/Optics/Beamline/&quot;&gt;http://www.aps.anl.gov/Xray_Science_Division/Optics/Beamline/&lt;/a&gt;</td></tr><tr><td>LYSO Scintillator</td><td>Proteus Inc</td><td></td><td>&lt;a href=&quot;http://www.apace-science.com/proteus/lyso.htm#top&quot;&gt;http://www.apace-science.com/proteus/lyso.htm#top&lt;/a&gt;</td></tr><tr><td>Coolsnap HQ2 CCD detector</td><td>Photometrics</td><td></td><td>&lt;a href=&quot;http://www.photometrics.com/products/ccdcams/coolsnap_hq2.php&quot;&gt;http://www.photometrics.com/products/ccdcams/coolsnap_hq2.php&lt;/a&gt;</td></tr><tr><td>ATC 2000 UHV sputtering deposition system</td><td>AJA International Inc</td><td></td><td>&lt;a href=&quot;http://www.ajaint.com/systems_atc.htm&quot;&gt;http://www.ajaint.com/systems_atc.htm&lt;/a&gt;</td></tr><tr><td>MICROPOSIT S1800 photoresist</td><td>Dow&amp;nbsp;</td><td></td><td></td></tr><tr><td>MICROPOSIT 351 developer</td><td>Dow&amp;nbsp;</td><td></td><td></td></tr><tr><td>MA/BA6 lithography system</td><td>SUSS MicroTec</td><td></td><td>&lt;a href=&quot;http://www.suss.com/en/products-solutions/products/mask-aligner/maba6/overview.html&quot;&gt;http://www.suss.com/en/products-solutions/products/mask-aligner/maba6/overview.html&lt;/a&gt;</td></tr><tr><td>Spin coater WS-400-6NPPB</td><td>Laurell Technologies Corporation</td><td></td><td>&lt;a href=&quot;http://www.laurell.com/spin-coater/?model=WS-400-6NPP-LITE&quot;&gt;http://www.laurell.com/spin-coater/?model=WS-400-6NPP-LITE&lt;/a&gt;</td></tr><tr><td>JBX-9300FS electron beam lithography system</td><td>JEOL</td><td></td><td>&lt;a href=&quot;http://www.jeolusa.com/PRODUCTS/PhotomaskDirectWriteLithography/ElectronBeamLithography/JBX-9500FS/tabid/245/Default.aspx&quot;&gt;http://www.jeolusa.com/PRODUCTS/PhotomaskDirectWriteLithography/ElectronBeamLithography/JBX-9500FS/tabid/245/Default.aspx&lt;/a&gt;</td></tr><tr><td>CS-1701 RIE system</td><td>Nordson March</td><td></td><td>&lt;a href=&quot;http://www.nordson.com/EN-US/DIVISIONS/MARCH/PRODUCTS/LEGACY/Pages/CS-1701-Anisotropic-RIE-Plasma-System.aspx&quot;&gt;http://www.nordson.com/EN-US/DIVISIONS/MARCH/PRODUCTS/LEGACY/Pages/CS-1701-Anisotropic-RIE-Plasma-System.aspx&lt;/a&gt;</td></tr><tr><td>Techni Gold 25E</td><td>Technic</td><td></td><td>&lt;a href=&quot;http://www.technic.com/eu/applications/industrial/industrial-chemistry/plating-chemistry&quot;&gt;http://www.technic.com/eu/applications/industrial/industrial-chemistry/plating-chemistry&lt;/a&gt;</td></tr><tr><td>Dektak-8 surface profiler</td><td>Bruker</td><td></td><td>&lt;a href=&quot;http://brukersupport.com/ProductDetail/1136&quot;&gt;http://brukersupport.com/ProductDetail/1136&lt;/a&gt;</td></tr><tr><td>MICROPOSIT 1165 remover</td><td>Dow&amp;nbsp;</td><td></td><td></td></tr></tbody></table>

measurement of x-ray beam coherence along multiple directions using 2-d checkerboard phase grating

一种用于一个技术过程使用一个单一的相位光栅干涉仪被报告给测量的同步辐射X射线源的横向相干性。测量是在先进光子源（APS）在阿贡国家实验室（ANL）的1-BM弯曲磁铁光束线证实。通过使用2-D棋盘π/ 2相移光栅，分别沿垂直和水平方向，以及沿45°和135°方向的水平方向上得到的横向相干长度。以下在本文中指定的技术细节，在相位沿着光束传播方向光栅的下游的不同位置进行测量干涉图。每个干涉的可见度值从分析其傅里叶变换图像的谐波峰提取。因此，沿各个方向上的相干长度可以从能见度的演变被提取的一个函数光栅到DETEC器的距离。连贯的同时测量长度在四个方向有助于确定高斯形的X射线源的相干性区域的椭圆形。多个方向干涉表征所报告的技术是选择适当的样本大小和方向，以及用于校正在相干散射实验部分相干效应很重要。还可以应用用于评估的X射线光学器件的相干性保持能力这种技术。

而详细的实验和仿真结果，可以在其他地方发现8，该部分仅显示选择的结果来说明上述测量和数据分析程序。 图1表示在APS 1-BM-B光束线实验设置。光束大小由一个1×1 平方毫米狭缝从弯曲磁体源放置在双晶单色（DCM）和25微米的上游限定。将DCM被调谐至18千电子伏的输出光子能量。 X射线束穿过放置在沿着光束路径的不同位置的几个铍窗（1毫米总厚度）。 <p class="jov...

Watch this Scientific Journal Video about Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating at JoVE.com

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

测量协议和数据分析程序，给出用于获得同步辐射X射线源的横向相干沿四个方向同时使用一个单一的2-D棋盘相位光栅。这个简单的技术可应用于的X射线源和X射线光学器件完成横向相干性的表征。

使用2-D棋盘相位光栅X射线束相干测量沿多个方向

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is ...

measurement-x-ray-beam-coherence-along-multiple-directions-using-2-d

Research

JoVE Journal

Engineering

9.6K 次观看.  Argonne National Laboratory. 测量协议和数据分析程序，给出用于获得同步辐射X射线源的横向相干沿四个方向同时使用一个单一的2-D棋盘相位光栅。这个简单的技术可应用于的X射线源和X射线光学器件完成横向相干性的表征。 

视频: Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the standard quantum limit or to cool mechanical systems to their quantum ground state. This is for example the case of future gravitational wave observatories, whose sensitivity to gravitational wave signals is expected to be limited in the most sensitive frequency band, by atomic vibration of their mirror masses. One promising approach being pursued to overcome this limitation is to employ higher-order Laguerre-Gauss (LG) optical beams in place of the conventionally used fundamental mode. Owing to their more homogeneous light intensity distribution these beams average more effectively over the thermally driven fluctuations of the mirror surface, which in turn reduces the uncertainty in the mirror position sensed by the laser light.
We demonstrate a promising method to generate higher-order LG beams by shaping a fundamental Gaussian beam with the help of diffractive optical elements. We show that with conventional sensing and control techniques that are known for stabilizing fundamental laser beams, higher-order LG modes can be purified and stabilized just as well at a comparably high level. A set of diagnostic tools allows us to control and tailor the properties of generated LG beams. This enabled us to produce an LG beam with the highest purity reported to date. The demonstrated compatibility of higher-order LG modes with standard interferometry techniques and with the use of standard spherical optics makes them an ideal candidate for application in a future generation of high-precision interferometry.

Large laser-interferometers are being constructed to create a new type of astronomy based on gravitational waves. Their sensitivities, as for many other high-precision experiments, are approaching fundamental noise limits such as the atomic vibration of their components. We are pioneering technologies to overcome these limits using novel laser beam shapes.

代高阶拉盖尔 - 高斯光束的高精度干涉

Thermal noise in high-reflectivity mirrors is a major impediment for several  types of high-precision interferometric experiments that aim to reach the  ...

科研

工程学

Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.&#160; Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.&#160; The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.&#160; The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.&#160; We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.&#160;&#160; This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.

The technique of femtosecond four-wave mixing is described, including spectrally-resolved and time-resolved configurations. We illustrate the utility of this technique for the investigation of crucial physical properties in the III-V diluted magnetic semiconductors, afforded by its nonlinearity and high temporal resolution.

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, ...

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels

Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.

可控合成和高度统一聚荧光追踪（<em&gt;ñ</em&gt; -isopropylacrylamide）微凝胶

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this ...

化学

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

量子干涉效应在硅谐振环光子源测量

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

Generation and Coherent Control of Pulsed Quantum Frequency Combs

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional states on-chip in a practical way have remained elusive due to the increasing complexity of the quantum circuitry needed to prepare and process such states. Here, we outline how high-dimensional, frequency-bin entangled, two-photon states can be generated at a stable, high generation rate by using a nested-cavity, actively mode-locked excitation of a nonlinear micro-cavity. This technique is used to produce pulsed quantum frequency combs. Moreover, we present how the quantum states can be coherently manipulated using standard telecommunications components such as programmable filters and electro-optic modulators. In particular, we show in detail how to accomplish state characterization measurements such as density matrix reconstruction, coincidence detection, and single photon spectrum determination. The presented methods form an accessible, reconfigurable, and scalable foundation for complex high-dimensional state preparation and manipulation protocols in the frequency domain.

A protocol is presented for the practical generation and coherent manipulation of high-dimensional frequency-bin entangled photon states using integrated micro-cavities and standard telecommunications components, respectively.

脉冲量子频率梳的产生与相干控制

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional ...

Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick tissue samples and organs in health and disease. By controlling the scanning pattern in multi-photon microscopy and applying appropriate numerical algorithms, we developed a striped-illumination approach, which enabled us to achieve 3-fold better axial resolution and improved signal-to-noise ratio, i.e. contrast, in more than 100 &#181;m tissue depth within highly scattering tissue of lymphoid organs as compared to standard multi-photon microscopy. The acquisition speed as well as photobleaching and photodamage effects were similar to standard photo-multiplier-based technique, whereas the imaging depth was slightly lower due to the use of field detectors. By using the striped-illumination approach, we are able to observe the dynamics of immune complex deposits on secondary follicular dendritic cells &#8211; on the level of a few protein molecules in germinal centers.

High-resolution intravital imaging with enhanced contrast up to 120 &#181;m depth in lymph nodes of adult mice is achieved by spatially modulating the excitation pattern of a multi-focal two-photon microscope. In 100 &#181;m depth we measured resolutions of 487 nm (lateral) and 551 nm (axial), thus circumventing scattering and diffraction limits.

生发中心的高度已解决活体条纹照明显微镜

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick ...

免疫与感染

Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser radiation. The method is based on the coherent sum of two uniform waves, previously encoded into a phase-only spatial light modulator (SLM) by spatial multiplexing of their phases. Here, the interference process is carried out by spatial filtering of light frequencies at the Fourier plane of certain imaging system. The correct implementation of this method allows arbitrary phase and amplitude information to be retrieved at the output of the optical system.
It is an on-axis, rather than off-axis encoding technique, with a direct processing algorithm (not an iterative loop), and free from coherent noise (speckle). The complex field can be exactly retrieved at the output of the optical system, except for some loss of resolution due to the frequency filtering process. The main limitation of the method might come from the inability to operate at frequency rates higher than the refresh rate of the SLM. Applications include, but are not limited to, linear and non-linear microscopy, beam shaping, or laser micro-processing of material surfaces.

We show how to encode the complex field of laser beams by using a single phase element. A common-path interferometer is employed to mix the phase information displayed into a phase-only spatial light modulator to finally retrieve the desired complex field pattern at the output of an optical imaging system.

利用相位空间光调制器建立激光光束的振幅和相位

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser ...

X-ray Beam Induced Current Measurements for Multi-Modal X-ray Microscopy of Solar Cells

X-ray beam induced current (XBIC) measurements allow mapping of&#160;the nanoscale performance of electronic devices such as solar cells. Ideally, XBIC is employed simultaneously with other techniques within a multi-modal X-ray microscopy approach. An example is given herein combining XBIC with X-ray fluorescence to enable point-by-point correlations of the electrical performance with chemical composition. For the highest signal-to-noise ratio in XBIC measurements, lock-in amplification plays a crucial role. By this approach, the X-ray beam is modulated by an optical chopper upstream of the sample. The modulated X-ray beam induced electrical signal is amplified and demodulated to the chopper frequency using a lock-in amplifier. By optimizing low-pass filter settings, modulation frequency, and amplification amplitudes, noise can efficiently be suppressed for the extraction of a clear XBIC signal. A similar setup can be used to measure the X-ray beam induced voltage (XBIV). Beyond standard XBIC/XBIV measurements, XBIC can be measured with bias light or bias voltage applied such that outdoor working conditions of solar cells can be reproduced during in-situ and operando measurements. Ultimately, the multi-modal and multi-dimensional evaluation of electronic devices at the nanoscale enables new insights into the complex dependencies between composition, structure, and performance, which is an important step towards solving the materials&#39; paradigm.

A setup for X-ray beam induced current measurements at synchrotron beamlines is described. It unveils the nanoscale performance of solar cells and extends the suite of techniques for multi-modal X-ray microscopy. From wiring to signal-to-noise optimization, it is shown how to perform state-of-the-art XBIC measurements at a hard X-ray microprobe.

太阳能电池多模态X射线显微镜的X射线光束诱导电流测量

X-ray beam induced current (XBIC) measurements allow mapping of&#160;the nanoscale performance of electronic devices such as solar cells. Ideally, XBIC is ...

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by local enhancement of electric field intensity that strengthens light-matter interactions, enabling applications such as surface-enhanced Raman scattering (SERS) and surface plasmon enhanced sensing. In the presence of magneto-optically active materials, the local field enhancement gives rise to anomalous magneto-optical activity. Typically, the confined modes of a given photonic crystal depend strongly on the wavelength and incidence angle of the incident electromagnetic radiation. Thus, spectral and angular-resolved measurements are needed to fully identify them as well as to establish their relationship with the magneto-optical activity of the crystal. In this article, we describe how to use a Fourier-plane (back focal plane) microscope to characterize magneto-optically active samples. As a model system, here we use a plasmonic grating built out of magneto-optically active Au/Co/Au multilayer. In the experiments, we apply a magnetic field on the grating in situ and measure its reciprocal space response, obtaining the magneto-optical response of the grating over a range of wavelengths and incident angles. This information enables us to build a complete map of the plasmonic band structure of the grating and the angle and wavelength dependent magneto-optical activity. These two images allow us to pinpoint the effect that the plasmon resonances have on the magneto-optical response of the grating. The relatively small magnitude of magneto-optical effects requires a careful treatment of the acquired optical signals. To this end, an image processing protocol for obtaining magneto-optical response from the acquired raw data is laid out.

Photonic band structure enables understanding how confined electromagnetic modes propagate within a photonic crystal. In photonic crystals that incorporate magnetic elements, such confined and resonant optical modes are accompanied by enhanced and modified magneto-optical activity. We describe a measurement procedure to extract the magneto-optical band structure by Fourier space microscopy.

光子纳米结构的光谱和角度解析磁-光学特性

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by ...

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared. A characterization method of such circuits is presented, which allows the output beam of integrated OPAs to be shaped and steered. Furthermore, using a wafer-scale characterization setup, several devices can easily be tested across multiple dies on a wafer. In this way, fabrication variations can be studied, and high-performance devices identified. Typical images of OPA beams are shown, including beams emitted from OPAs with and without a uniform waveguide length, and with varying numbers of channels. In addition, the evolution of output beams during the phase optimization process and beam steering in two dimensions is presented. Finally, a study of the variation in the beam divergence of identical devices is performed with respect to their position on the wafer.

Here, we describe the operation of a SiN integrated photonic circuit containing optical phased arrays. The circuits are used to emit low divergence laser beams in the near infrared and steer them in two dimensions.

晶圆级试验站上SiN集成光学相控阵列的特性

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for ...