作者想承认所罗门提供样品。这项工作得到了国家科学基金会 (DMR-1452840) 的支持。

警告: 请注意对齐时激光散射的可能危险。佩戴适当的安全护目镜保护。为了便于对齐过程, 需要红外查看器 (IR 查看器)。IR 敏感的荧光卡也有帮助, 但没有必要. 
 1. 样品制备 <ol> <li> 使用菱形抄写员在样品的顶部表面边缘进行微小的划痕。用两对平端镊子将样品放在划痕两侧。应用一个外旋转扭矩与镊子和样品将劈. 
	注意: 长划痕是不必要的促进裂解, 它可能会削减通过波导层使光耦合不可能。切割的脸是微妙的, 任何触摸它的表面可能会损害波导管的脸. </li>
	<li> 用导热银漆或银环氧树脂将劈裂试样贴在铜样品板上. 
	注: 切割面应与安装板的边缘齐平, 使励磁激光器能在不受干扰的情况下命中样品面. </li>
	<li> 在低温中安装铜板, 以便通过低温窗口可光学地访问切割面和样品表面. </li>
</ol> 2。共振励磁路径的对准 注意: 为了使耦合效率最大化到波导中, 入射励磁梁的剖面必须与假想的向后传播光束相匹配, 从而退出波导. 
<ol> <li> 将励磁激光束粗对齐到试样的切割面. 
	<ol> <li> 使用光纤耦合器 FC0 和镜像 M0 的自由度, 在安装励磁透镜之前, 将励磁光束定向到样品的切割面上. </li>
		<li> 将激发光束水平地与光学表相对, 并与样品的平面相对应. </li>
	</ol> </li> <li> 安装励磁目标和 #160; E obj <ol> 将非球面透镜 E <li> obj 置于平移式装载中, 具有三度平移自由度。将 e 的 obj 放在激光器上, 并设置高度 #160; e obj 与示例的中心相同. </li>
		<li> 沿励磁路径在样品后面设置一个白纸屏幕。使用 IR 查看器观察在纸上的一个亮点, 因为激光通过样品. </li>
		<li> 幻灯片和 #160; E obj 向样品缓慢地移动, 直到在纸上看到一个清晰的样品轮廓图。调整和 #160 的高度和横向位置; E obj 使剪影位于明亮点的中央. </li>
		<li> 保持滑动 E obj 向样品缓慢移动, 屏幕上的侧面影像图像会放大。同时, 调整 E obj (左/右) 的横向位置以补偿侧面影像图像的水平移动. 
		注意: 在 E obj 的缓慢移动过程中, 衍射条纹将开始出现在某个点上。这提供了一个新的参考, 把焦点点在表面层的样品. </li>
		<li> 保持滑动和 #160; E obj 慢慢地向样本。在 e obj 的每个位置, 向左/向右移动 e obj 会增加条纹间距, 直到只有一个可见的边缘在屏幕上查找条纹. 
		注意: 将有两组条纹, 一个在左边, 一个在样品表面的右边. </li>
		<li> 定位幻灯片 E obj Eobj 在最小化可见条纹数的位置. </li>
	</ol> </li> <li> 对齐望远镜镜头 E1 和 E2 <ol> <li> 将镜片 E1 和 E2 插入以激光束为中心的励磁路径。位置 E2 与 #160 分离; E obj 由它们的焦点长度之和。将 E1 和 E2 之间的分隔设置为其焦距的总和, 例如 、f 1 + f 2 = 150 mm 和 #160; </li> <li> 使用 IR 查看器观察纸张的侧面影像和衍射图案。调整 E1 的高度以中心的剪影在明亮的激光照明点的中心. </li>
		在调整 E1 的横向位置时, <li> 滑动 E2 朝向或远离 E1。安全 E1 和 E2 在两个边缘组要么消失, 要么在视图中显示最小的条纹数. 和 #160; </li> <li> 在 E1 前插入垂直方向的偏光器, 并将其集中在励磁光束上. #160; 注意: 有些偏振微楔角, 在这种情况下, 励磁梁将经历一个角偏差。使用 E1 和 E2 来补偿这种偏差. </li>
	</ol> </li> </ol> 3。光致发光采集路径的对准 注意: 在集合路径中生成的成像系统的性能主要取决于 L obj 的定位精度, 因为它的焦距很短 (f obj = 10mm, NA = 0.55)。在 L obj 的对齐过程中涉及两个常规步骤: 使用氖激光器进行粗对准, 以及使用 GaAs 的光源和大容量激子发射进行微调。这些对准步骤与样品在室温下进行. 
<ol> <li> 对齐上述带隙 (氖) 励磁路径和安装摄像头: <ol> <li> 一对以上带隙激光束 (氖) 成单模光纤. </li>
		<li> 通过镜像 M3 将光纤准直器的输出光束直接 FC1 到样品上. </li>
		<li> 倾斜 FC1 水平居中, 将样品上的激光点放在离切割边缘大约1毫米的地方。水平倾斜 M3, 将激光束的后反射移到入射光束的正上方或下方。重复此过程多次, 直到满足两个条件. </li>
		<li> 垂直倾斜 FC1 和 M3, 使氖光束与光学工作台相对水平, 并将其对准样品. </li>
		<li> 使用 IR 查看器在样品上定位谐振激光器和氖激光点。检查氖激光光斑的中心与谐振激光光斑的高度相同。如果没有, 使用 FC1 和 M3 匹配的横梁高度, 同时保持氖光束水平与表. </li>
		<li> 将 non-polarizing 光束分配器立方体 (90:10) NPBS 插入到氖路径中。中心的立方体在事件氖光束. </li>
		<li> 将分束器输出的两个光束定位到集合路径, 一个来自示例的反射, 另一个来自多维数据集内的内部反射. </li>
		<li> 将立方体旋转一个小角度 (〜5度), 这样两个光束可以在出口处很容易地分开。从样品表面反射的光可以用来作为对齐相机的粗略指南. 
		注意: 当多维数据集绕垂直轴旋转时, 内部反射光束的方向不会改变. </li>
		<li> 根据 "光学" 选项卡对多维数据集进行级别le 通过确保氖梁对应的内部反射在立方体内是在同一高度的传入光束. </li>
		<li> 将红外敏感相机放在背面反射的氖光束的路径中。使用管透镜 L 凸轮 , 焦距为 200 mm, 将样品图像聚焦到相机上. 
		注: 国产管系统用于对镜头 L 凸轮 进行内部显示, 如 图 1 所示, 它可防止照相机检测到杂散光室的光线. </li>
		<li> 设置一个 800 nm long-pass 过滤器, F1, 在 L 凸轮 过滤出氖光, 这允许观察 PL 从样品与照相机. </li>
	</ol> </li> <li> 安装和优化镜头的位置 L obj <ol> <li> 将非球面透镜和 #160; L obj 在平移式装载中, 具有三度的平移自由度。中心和 #160; L obj 在氖激光器上, 并将分离从样本设置为焦距, f obj = 10 mm. </li>
		<li> 设置透镜对 L1 和 L2 (f 1 = f 2 = 50 mm), 方法是使用 X Y 平移装入, 其中一侧固定, 另一侧在由千分尺控制的横向平面上移动. 
		注: 镜头 L2 进入安装的活动侧。L1 由透镜管持有, 并附着在固定的安装一侧。管系统提供了自由调整两个镜头之间的距离, 拧入/出透镜管持有 L1 沿光轴. </li>
		<li> 将两个镜片之间的距离设置为 100 mm, 通过调整千分尺来设置 L2 在安装中心的位置. </li>
		<li> 将 L1 和 L2 镜头组合插入到 NPBS 和低温之间的氖路径中。将 L1 和 L obj 之间的距离设置为 f obj + f 1 。中心 L1 和 L2 在事件氖的灯光下. </li>
		<li> 将光源和薄膜插入到集合路径中, 如 图 1 所示。将透镜 K4 和 L2 之间的距离设置为其焦距的总和. </li>
		<li> 通过调整光源的角度来 L2 照明光束的中心. </li>
		<li> 调整薄膜的角度, 使背部反射的光照在相机图像中可见, 氖激发引起的 PL 点. 
		注: 为了对准, 你可以关闭现场的膜片, 以找到中心的照明区域. </li>
		<li> 仅使用照明灯, 通过查看照相机在样品上找到表面缺陷或灰尘。通过横向移动 L2, 根据需要搜索样品的其他部分. </li>
		<li> 轻微点击 L obj 沿光轴进出, 使缺陷或尘埃的边缘最锋利. </li>
		<li> 将 L2 移回装载的中心. </li>
		<li> 查看相机上的氖激发 pl 点, 并将 L obj 水平移动, 使 pl 点从样本的已切割边缘 1-2 mm. 
		注: 对于小于 1 mm 的距离, 将通过目标 L obj 收集来自样品的切割边缘的激光散射。在离切割面太远的距离上, 励磁光束在到达量子数据量之前会经历衰减, 从而降低了最大的激发功率. </li>
		<li> 水平移动 L2, 直到样品的边缘在光照下显示在相机上. </li>
		<li> "渐变 L" obj 垂直移动以在试样的劈边上寻找明亮的激光光斑, 这是由于共振激发光束在试样的劈裂面上的散射引起的. </li>
		<li> 将氖激发的 PL 点放在试样的切割边缘上的明亮光斑上. </li>
	</ol> </li> <li> 对氖励磁路径的重新调整, 关于 L obj 的新位置. 
	注: 为了最大限度地扫描面积和最小化晕, 有必要重新励磁光学和励磁光束就位置的 L obj 。
	<ol> <li> 移除 L1 和 L2。将励磁梁居中并 #160; L obj , 同时确保光束位于样本的曲面法线方向. </li>
		<li> 中心 L2 在装载上。中心 L1 和 L2 在入射励磁梁上。设置 L1 和 #160 之间的距离; obj 为两个焦点长度的总和, 即 , f 1 + f obj . </li>
		<li> 重新定位 L 凸轮 这样, 它是集中在反射氖光束。重新定位相机, 使氖兴奋 PL (使用 long-pass 过滤器) 在图像上居中. </li>
		<li> 调整照明灯和薄膜的角度, 使光照在 L2 和氖励磁引起的 PL 点上居中. </li>
	</ol> </li> <li> 对齐镜像 M1 和 M2. 
	注: 通过光谱仪向后定向的激光将促进对准。
	<ol> <li> 从照相机的示例中监视氖激发 PL。将虹膜 (虹膜 A) 放在薄膜和 M1 之间的 PL 上. </li>
		<li> 中心透镜 L 规范 在反向光束上, 并将其一个焦距 f 规范 远离光谱仪的入口狭缝. </li>
		<li> 通过反射两个反射镜、M1 和 M2, 从光谱仪向样品发送反向光束. </li>
		<li> 在 M2 和 L 规范 之间设置另一个虹膜 (虹膜 B) 并将其置于反向光束的中心. </li>
		<li> 引导 M2 到中心的反向光束虹膜 a. 引导 M1 中心的 PL b. 重复此过程多次, 直到满足两个标准. </li>
		通过监视房间光线的零阶衍射, <li> 在 CCD 上定位分光计的入口狭缝 (30 #956; m 宽度) 的中心. </li>
		<li> 打开光谱仪的入口狭缝。通过使用 800 nm 长通滤波器, 可以在 CCD 上观察到氖激励下样品的 PL. </li>
		<li> 引导 M1 在分光计的入口狭缝和 CCD 的中间高度中心这个点, 并引导 M2 到虹膜的反向光束中心. 重复此过程几次, 直到满足两个标准. </li>
		<li> 镜头对 L3 和 L4 的对齐: 在 PL 集合路径中的位置 L3, 位于 f 2 + f 3 远离镜头 L2。将 L4 放置到集合路径中, 其焦点长度的总和与 L3 分开, f 3 + f 4 。在 CCD 上调整 L4 的侧位以使 PL 点居中. </li>
	</ol> </li> </ol> 4。PL 集合路径与谐振励磁路径的重叠 <ol> <li> 将样本冷却到 4.2 K。利用上述波段的激励, 使用光谱仪来确定润湿层的发射波长 (通常在 880 nm 左右). </li>
	<li> 在 L 凸轮前面设置一个 800 nm long-pass 过滤器 F1, 以阻止氖光。在照明灯的帮助下, L2 水平移动, 在相机上定位样品的边缘. </li>
	<li> 设置侧面激发波长与润湿层共振。在相机上的样品的边缘找到一个明亮的散射点. </li>
	通过调整 E1 的侧位, <li> 观察 #34、条纹图案和 #34;通过横向移动 E1 使条纹的强度最大化. 
	注: #34; 条纹和 #34; 润湿层发射, 这意味着激发光束被耦合到样品的波导中. </li>
	<li> 垂直调整 E1 以移动条纹, 使其与氖激发的 PL 点重叠. </li>
	<li> 记录润湿层 PL 的强度. 在一个方向调整 E2, 然后优化 E1 的位置; 再次记录 pl 的强度, 并与以前的值进行比较. </li>
	<li> 如果强度增加, 则重复 E2 在同一方向的调整。如果强度降低, 则反转 E2 的调整。重复此过程可找到 E1 和 E2 的最佳位置. </li>
</ol> 5。单量子点的共振激发 p 类 = "jove_content">> 注意: 有两种可能的方法来实现谐振激励的单个量子数: (1) 调谐的激光激发频率匹配特定的量子共振;或 (2) 扫描的激光频率跨越的共振能量的量子, 直到共振荧光从一个单一的量子探针观察. 
<ol> <li> 方法 (1)-目标激发: <ol> <li> 设置分光计, 以监视在上述带隙激励下的量子点集合的发射波长中心的一阶衍射。打开光谱仪的入口狭缝. </li>
		<li> 调整上述波段励磁的功率, 直到发光背景出现由于润湿层的连续尾的励磁状态。关闭入口狭缝到30和 #956; m. </li>
		<li> 侧移 L2 以找到合适的量子, 例如, 在视图中最亮的一个。记录光谱的波长和 #160; 和 #955; 用光谱仪测量的 量子数 . </li>
		<li> 调谐谐振激励激光器的波长与 #955 相同的值; 
		注意: 通常, 光谱仪可以从光学中提取共振激发激光器的微弱信号。如果没有, 将分裂的励磁光束定向到光谱仪中. </li>
		<li> 通过微调激励激光器的频率, 使 CCD 上的量子荧光和 #39 强度最大化. 
		注意: 对于某些量子, 需要少量的氖光才能使量子点共振激发 10 , 31 , 32 。所需的氖激光功率通常是如此 low-a 几百纳瓦-没有任何荧光造成的完全由这氖光束可以检测到的 CCD. </li>
		<li> 通过调整透镜 E1 的高度和横向位置以及透镜 E2 的轴向位置, 从而最大限度地提高了量子位的 PL 强度。联合优化透镜 E1 和 E2 的位置, 以最大限度地提高量子点的共振荧光强度. </li>
	</ol> </li> <li> 方法 (2)-光谱搜索: <ol> <li> 设置光谱仪, 以监测一阶衍射在发射波长中心的量子点合奏。打开光谱仪的入口狭缝. </li>
		<li> 调整激发激光器的频率, 使其跨越能量范围。一个共振兴奋的量子点将出现在 CCD 上, 作为一个斑点包围几个通风环。选择一个明亮的量子. </li>
		<li> 通过微调激发激光器的波长来最大化其 PL 强度. </li>
		<li> 通过调整 E1and 的高度和横向位置来最大化圆点的 PL 强度, E2 透镜的轴向位置。联合优化透镜 E1 和 E2 的位置, 以最大限度地提高量子点的共振荧光强度. </li>
	</ol>
	</li>
</ol>

<ol>
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作者没有什么可透露的。

该协议的关键步骤是: 模式匹配和对波导模式的激励光束对准;和正确的对准和集中的收集光学。这些步骤中最困难的部分是初始对准;优化已对齐的设置的耦合是相对简单的。重叠的集合和励磁区域是一个步骤, 是简单的能力, 图像的样品在相机上, 但是非常困难的, 没有这种能力。为了有高质量的成像, 正确的科勒照明是至关重要的。科勒照明的主题超出了本协议的范围, 但在显微镜下是一个众所周知的概念, 在已发表的文献34,35中进行了全面的讨论。
这里提到的透镜焦距是典型的, 但不是必需的。不同的低温和其他因素可能强加对光学安排的另外或不同的要求。在这种情况下, 在设计过程中正确选择透镜焦距是满足励磁路径和科勒光照在采集路径中的模式匹配要求的关键。如果用焦距的总和将镜片分开, 科勒照明就会得到满足。适当的模式匹配到波导要求尽可能高的 NA, 这意味着光束必须填补 Eobj的光圈。目标坐落在一个自制的燕尾导轨 XYZ 安装, 只在室温下移动, 因为它位于低温的代码空间内。这个 close-to-sample 位置允许使用一个大的 NA 透镜, 同时最小化热变化在透镜支架, 增加机械稳定性。这种情况下的目标是非球面单线态透镜由于空间限制。如果有更多的空间可用, 商业多目标可以被用来改善成像质量, NA, 和放大。实验装置可以扩展, 以允许共焦共振或近共振励磁通过取代 M3 与一个分色镜和指挥一个励磁光束通过两个分色和分束器 NPBS。
如果激光背景太强, 则励磁光束与波导的耦合较差是可能的原因。由于处理不当, 在切割面上的粗糙度、划痕或污染会使联轴器减少。将被耦合的面孔绝不能触及任何事物。这是可能的, 但很难清洁的裂面污染, 但粗糙和划痕是永久性的。如果表面质量是一个问题, 在切割面上可以尝试不同的位置, 但可能需要新的劈裂。强激光散射背景也可能是由样品表面的尘埃散射产生的激发光的不耦合部分引起的。另一种可能性是, 视野太靠近样本的边缘, 光从边缘散射进入集合路径。最后, 可能是激光功率太高了。通常, 在图 1中显示的功率计上, 激发激光功率的范围为0.5 到10µW。除了减少激光散射源外, 通过在采集路径中添加水平偏光片可以滤除散射。然而, 要看到这种情况下的量子荧光, 需要一个量子位的偶极矩与垂直方向不对准。
励磁极化仅限于一个选择;在这种情况下, 它是垂直极化。这是因为三限制。首先, 将激励光束的传播方向限制在样本平面内。第二, 极化必须与传播方向垂直。第三, 量子偶极矩位于样品平面上。如果, 在这种情况下, 激发光束水平传播, 那么唯一的选择极化, 可以激发量子是垂直的。相比之下, 由于激光散射的抑制主要是通过在波导模式11内的激光约束来实现的, 所以检测极化对其没有约束。另一个限制是, 这种激励方案需要一个波导来引导光的量子点, 一个结构, 可能是不可行的所有样本。将其与暗场共焦激发技术1进行比较, 该方法使用交叉偏振抑制激光散射。在这种情况下, 激发可以使用任意极化, 但检测极化必须是正交的。
在共振激励下的单量子点被证明为具有高亮度、窄线宽和高不可36的优良单光子源。该协议提供了一种可行的方法来利用自组装的量子系统的这些特殊性质的各种应用, 如量程信息和线性光学量子计算。此外, 光子纠缠与另一个光子或电子自旋将需要收集不考虑极化, 这是这个方法的一个特点。

单量子发射器与荧光检测相结合的共振激励是一种长期的实验性挑战, 主要是由于无法光谱强激发散射的弱荧光判别。然而, 这一困难在过去十年中成功地克服了两种不同的方法: 基于偏振判别的暗场共焦激发1,2,3,4 ,5, 基于空间模式判别的正交励磁检测6,7,8,9,10,11, 12、13、14。这两种方法都表现出强烈的抑制激光散射的能力, 因此在各种实验中被广泛采用, 例如, 自旋光子纠缠的观测5,15, 16 ,演示的着装状态2,7,12,17,18,1920,22,23,24,25,26, 并对受限旋转的操作进行了3,27,28,29,30。这两种方法都不能普遍适用于各种情况;每个都限于某些特定的条件。暗场技术利用光子自由偏振度来抑制激光散射。这项技术有几个优点。例如, 没有对定义良好的波导模式的要求, 这将启用共聚焦的实现。共焦实现允许圆极化励磁和可能更紧的焦点的励磁束在量子发射器, 导致更高的激发强度。然而, 这种极化选择法限制了检测极化与励磁极化的正交性, 从而防止了荧光极化特性的完全表征。与之相比, 空间模式判别法利用励磁传播模式与检测光束之间的正交性, 来抑制激光散射4, 从而保持了检测极化的完全自由。这一技术的约束是在样品中的波导结构的必要性, 提供了一个与探测模式正交的励磁模式, 并限制励磁极化与光束的传播方向垂直.
在这里, 我们演示了一个协议, 建立一个 free-space-based 正交励磁检测设置的共振荧光实验。与在空间模式判别方面的开创性工作相比, 当光纤被用来将光耦合到空腔6时, 该协议在可用空间中提供了一个解决方案, 并且不需要动态组件来装载示例或纤维在低温。对励磁光束方向和检测路径的精细控制由低温外部的光学操纵, 而非球面单线态透镜则作为低温冷区内的聚焦目标。我们提供有代表性的图像的关键对准步骤的过程中实现共振激发和检测的荧光从一个单一的量子点。
本演示所用的样品是通过分子束外延 (外延) 生长的。铟量子点 (量子) 嵌入在由两个分布式布拉格反射器 (DBRs) 限定的 GaAs 间隔中, 如图 1中示例的放大视图所示。在 DBRs 之间的 GaAs 间隔作为波导, 其中的励磁束被限制在全内反射。DBRs 也充当 wavevectors 的 high-reflectivity 镜, 对样品平面来说几乎是正常的。这形成一个法布里-珀罗模式, 量子夫妇发出荧光。法布里-珀罗模式必须与量子的发射波长λ共振, 这要求 gaas 间隔是一个整数倍数的λ/n, 其中 n 是 gaas 折射指数。在这个演示中, GaAs 间隔的厚度被选择为 4λ/n, 大约是1µm, 以便在入射激发光束的衍射有限光斑尺寸附近。更窄的间隔将导致励磁光束的耦合效率降低到波导管模式。
实验设置如图 1所示。为了最大限度地提高耦合效率, 选择一个非球面单目标 Eobj , 数值孔径 NA = 0.5, 焦距为 8 mm, 将励磁光束聚焦在试样的劈裂面上。Keplerian 望远镜 (由透镜对 E1 和 E2 组成) 在励磁路径中的作用是两倍的: (1) 填充励磁目标 Eobj的孔径, 因此励磁光束被紧紧地聚焦在波导的更好模式匹配 (这种实现的准直光束直径是2.5 毫米), 和 (2) 提供三自由度, 以机动的焦点的励磁梁在切割面的样品。镜头 E1 安装在 X Y 平移安装上, 提供了两自由度, 可以自由地在切割试样面的平面上移动励磁点。镜头 E2 安装在旋转变焦外壳上, 提供了选择样品中焦点深度的自由。这三自由度允许我们在不需要样本本身运动的情况下, 优化单个量子数的共振激励。
在荧光收集路径, 类似的镜头配置 (Lobj, L1, 和 L2) 是用来允许检测的荧光从不同部分的样本。从样品的光线集中在两个管透镜之一的红外敏感相机 (l凸轮) 或入口狭缝光谱仪 (l规范)。L1 沿 z-axis 的运动调整图像的焦点, L2 的横向平移使图像在样品的平面上扫描。L1 和 L2 的焦距是相等的, 所以它们的放大倍数是统一的。这样做是为了最大限度的范围 L2 可以翻译之前, 晕发生。
为了便于对量子点的对准和定位, 基于科勒照明的国产照明灯被纳入到安装中, 如图 1所示。科勒照明的目的是为样品提供均匀的光照, 并确保我光照光源的法师在样本图像中不可见。照明灯和采集路径的镜头配置是精心设计的, 以分离样品和光源的共轭图像平面。集合路径中的每个镜头都是通过其焦距的总和与相邻的透镜隔开的。这可以确保无论在何处的样品图像是在焦点-例如在相机的传感器-光源图像是完全焦。同样, 在光源图像聚焦的地方--例如目标的后焦平面--样本图像是完全焦的。光源是一个商业发光二极管 (LED) 发射在 940 nm。光圈膜片使照明强度的调整, 和场膜片确定的视野要照亮。实现均匀光照的关键是将透镜 K4 和 L2 之间的距离设置为两个透镜焦距的总和, 并确保 Lobj的光圈不被光照所充填。在此协议中, 光照还用于优化 Lobj和示例之间的距离。
目标 Lobj和任一管透镜在相机或光谱仪上提供20x 的放大倍数。在 lobj和 l规范之间的透镜对 L3 和 L4 形成另一 Keplerian 望远镜, 它为光谱仪的电荷耦合器件 (CCD) 上的图像提供额外的4x 放大倍数。增加镜头 L3 和 L4 的结果, 总放大率为 80x, 这是必要的空间区分荧光从附近的量子. L3 和 L4 安装在翻转支架上, 以方便放大倍数的切换, 因为20x 放大倍数在示例上提供更大的视图字段。
为了使采集路径的视场与励磁光束通过波导的路径重叠, 量子点润湿层连续的发射是有帮助的。通过测量上述带隙激励下试样的发射光谱, 可以确定润湿层的发射波长。对于我们的样品, 润湿层放射发生在大约880毫微米在 4.2 K。通过将一个cw激光束在 880 nm 连接到样品的波导中, 你可以观察 PL 从润湿层形成的条纹图案, 在伴随的视频中显示。条纹揭示了被耦合到波导中的激发光的传播路径。这种条纹的存在结合了图像表面的能力, 使对齐直接。

<table>
	<tbody>
		<tr>
			<td>Tunable external cavity diode laser</td>
			<td>Toptica Photonics</td>
			<td>DL-Pro</td>
			<td></td>
		</tr>
		<tr>
			<td>Closed-cycle cryostat</td>
			<td>Montana Instruments</td>
			<td>Cryostation</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrometer, 750 mm focal length</td>
			<td>Princeton Instruments</td>
			<td>SpectraPro 2750</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermoelectrically cooled charge-coupled device</td>
			<td>Princeton Instruments</td>
			<td>Pixis 100BR-eXcelon</td>
			<td></td>
		</tr>
		<tr>
			<td>HeNe laser</td>
			<td>JDSU</td>
			<td>1125P</td>
			<td></td>
		</tr>
		<tr>
			<td>Infrared sensitive camera</td>
			<td>Sony</td>
			<td>NEX-5TL</td>
			<td>IR blocking filter removed</td>
		</tr>
		<tr>
			<td>Power meter and detector</td>
			<td>Newport</td>
			<td>1918-C, 918D-IR-OD3</td>
			<td></td>
		</tr>
		<tr>
			<td>Adjustable aspheric fiber collimator</td>
			<td>Thorlabs</td>
			<td>CFC-8X-A</td>
			<td></td>
		</tr>
		<tr>
			<td>Air-Spaced Doublet Collimator</td>
			<td>Thorlabs</td>
			<td>F810APC-842</td>
			<td></td>
		</tr>
		<tr>
			<td>Protected Silver Mirrors x 5</td>
			<td>Thorlabs</td>
			<td>PF10-03-P01</td>
			<td></td>
		</tr>
		<tr>
			<td>Flip mounts x 2</td>
			<td>Thorlabs</td>
			<td>FM90</td>
			<td></td>
		</tr>
		<tr>
			<td>Aspheric condenser lens, f = 20 mm; K1</td>
			<td>Thorlabs</td>
			<td>ACL2520-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Best form spherical lens, f = 50 mm; E2, L1, L2, K2</td>
			<td>Thorlabs</td>
			<td>LBF254-050-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Best form spherical lens, f = 100 mm; E1, L4, K3, K4</td>
			<td>Thorlabs</td>
			<td>LBF254-100-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Best form spherical lens, f = 200 mm; Lspec, Lcam</td>
			<td>Thorlabs</td>
			<td>LBF254-200-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Plano-convex lens, f = 400 mm; L3</td>
			<td>Thorlabs</td>
			<td>LA1172-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Molded glass aspheric lens, f = 8 mm; Eobj</td>
			<td>Thorlabs</td>
			<td>C240TME-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision asphere, f = 10 mm; Lobj</td>
			<td>Thorlabs</td>
			<td>AL1210-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Longpass Filters, 800 nm, x2</td>
			<td>Thorlabs</td>
			<td>FEL0800</td>
			<td></td>
		</tr>
		<tr>
			<td>Non-polarizing beam splitter cube (NPBS)</td>
			<td>Thorlabs</td>
			<td>BS029</td>
			<td></td>
		</tr>
		<tr>
			<td>Pellicle beam splitter</td>
			<td>Thorlabs</td>
			<td>BP108</td>
			<td></td>
		</tr>
		<tr>
			<td>Polarizer</td>
			<td>Thorlabs</td>
			<td>LPNIRE100-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Light emitting diode, 940 nm</td>
			<td>Thorlabs</td>
			<td>M940D2</td>
			<td></td>
		</tr>
	</tbody>
</table>

resonance fluorescence of an ingaas quantum dot in a planar cavity using orthogonal excitation and detection

同时进行共振激发和荧光检测的能力对于量子点 (量子) 的量子光学测量是非常重要的。没有荧光检测的共振激励-例如差分传输测量-可以确定发射系统的某些特性, 但不允许基于发射的光子的应用或测量。例如, 光子相关性的测量、Mollow 三重的观察以及单光子源的实现都需要收集荧光。非相干激发与荧光检测-例如, 上面带隙励磁-可以被用来创造单一的光子源, 但由于激发环境的干扰, 减少了光子的不可。基于量子的单光子源将不得不共振激发, 以具有高光子不可, 同时收集光子将是必要的, 以利用它们。我们演示了一种方法, 共振激发一个单一的量子, 嵌入在一个平面腔通过耦合励磁梁从样品的切割面, 而收集的荧光沿样品的表面法线方向。通过将励磁光束与腔体的波导模式进行仔细匹配, 激发光可以耦合到腔内, 并与量子点相互作用。散射光子可以耦合到腔的法布里-珀罗模式, 并在表面正常方向上逃逸。该方法在检测极化时允许完全自由, 但励磁极化受励磁光束传播方向的限制。从润湿层的荧光提供了一个指南, 使收集路径对齐的励磁梁。激发和探测模式的正交性使得单个量子数的共振激励具有可忽略的激光散射背景。

图 1显示了完成单个量子点共振激发所需设备的一个特定实现。其他认识是可能的, 但关键的组分是: 励磁路对耦合波导;引导荧光探测器的采集路径;沿采集路径激发的共焦励磁路径;和照明路径, 使样品表面成像。
图 2显示了两个具有代表性的 RPLE 频谱。它们是从一个中性量子点 (图 2(a) 和 (b)) 和一个带电的量子点 [图 2(c) 和 (d)] 中收集的。带电量子的精确电荷状态不能通过检测频谱来确定。为了达到最佳的信噪比, 激光散射必须保持在最低限度。图 2(a) 和 (c)中最右边的图像显示了激发激光远谐共振时的散射背景。激光散射比量子荧光光谱弱得多, 但为了说明典型的散射模式, 图像的放大率分别为284和23倍。如果在对准中遇到这些图像, 就意味着存在强激光散射。多个原因可能导致此结果, 例如耦合到波导管的失调, 波导管的切割面上的划痕, 太靠近样品的边缘的视野, etc。关于每一点的详细讨论在本议定书的讨论部分中提供。
在平面微腔中, 共振激发的量子数的图像通常会有围绕它的环的中央盘, 如图 3所示。这种模式的结果从量子位的耦合到平面波征的腔, 其传播方向是波长依赖33。因此, 一个单一波长的荧光从空洞的凹锥中出现, 其顶点角由发射的波长决定。当这盏灯被物镜准直并聚焦于显像管透镜时, 形成的图像具有环形结构, 如图 2和图 3所示。圆环和盘的半径将由尖顶角度和因而发射波长决定。发射波长越小, 顶点角越大, 半径越小。最小的可能顶点角是零, 这意味着有一个长的发射, 可以逃脱腔的截止。最大可能的顶点角由目标透镜的 NA 确定, 这意味着可以由光学系统收集的发射短波截止。一个目标与一个更大的 NA-或添加一个固体浸没透镜-将延长这一低端的集合带到较短的波长。另一方面, 除了改变样本结构外, 不能修改集合带的长波长端。图 3显示了从最小到截止波长不等的不同发射波长的量子的荧光图像。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56435/56435fig1.jpg"> 
图1。实验的示意图。 通过将窄线宽 (1 MHz) cw激光束耦合到样品的波导中来实现单个量子数的共振激发, 如橙色路径所示。样品的光致发光是从法布里-珀罗模式, 沿着红色路径收集的。氦氖 (氖) 激光器提供了上述带隙励磁 confocally, 沿着绿色路径。国产照明灯提供了样品表面的均匀照明与 940 nm 光, 如黄色路径所示。请注意, 示意图不缩放。FC: 光纤耦合器;广告: 光圈膜片;FD: 野战膜片;政客: 偏光片;F: long-pass 过滤器;NPBS: non-polarizing 光束分配器立方体;DBR: 分布式布拉格反射镜;CCD: 电荷耦合器件;LED: 发光二极管。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56435/56435fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56435/56435fig2.jpg"> 
图2。单个量子点的共振荧光。 (a) 在不同的 detunings 上的中性量子点的荧光图像, 在每个图像的顶部以线性频率表示。零失谐对应于927.8597 毫微米。(b) 同一个中性量子点的 RPLE 谱, 将 PL 强度与中心周围直径8像素的圆形区域相结合。(c) 不同 detunings 的带电量子位的荧光图像, 在每个图像的底部以线性频率表示。零失谐对应于927.653 毫微米。(d) 同一带电量子点的 RPLE 谱, 将 PL 强度与中心周围直径12像素的圆形区域相结合。(e) 在低能量峰值共振激励下 (a) 中的中性量子点的二阶相关测量。(a) 和 (c) 中最右边的帧是远谐的激励图像, 其强度分别为284和 23, 以显示低激光散射背景。请注意, (a) 和 (c) 的颜色比例不同, 但在单个次要中共享。(b) 和 (d) 中的归一化 RPLE 强度由橙色点描述, 而蓝色方块则分别表示与 (a) 和 (b) 中所示图像对应的数据。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56435/56435fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56435/56435fig3.jpg"> 
图3。谐振荧光从八不同的点在不同的波长在腔模式。 共振波长显示在每个图像的顶部。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56435/56435fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection at JoVE.com

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection

单自组装量子点的共振激励可以用一种与荧光采集模式正交的激励模式来实现。我们演示了一个方法使用的波导和法布里-珀罗模式的一个平面微腔周围的量子点。该方法允许完全自由的检测极化。

用正交激励和检测方法研究平面腔内铟量子点的共振荧光

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). ...

resonance-fluorescence-an-ingaas-quantum-dot-planar-cavity-using

Nanyang Technological University

Research

JoVE Journal

Engineering

9.1K 次观看.  West Virginia University. 单自组装量子点的共振激励可以用一种与荧光采集模式正交的激励模式来实现。我们演示了一个方法使用的波导和法布里-珀罗模式的一个平面微腔周围的量子点。该方法允许完全自由的检测极化。

视频: Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

梯度回波量子存储在温暖的原子蒸气

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

科研

工程学

Analysis of Contact Interfaces for Single GaN Nanowire Devices

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit a strong degradation after annealing due to the occurrence of void formation at the contact/SiO2 interface. This void formation can cause cracking and delamination of the metal film, which can increase the resistance or lead to a complete failure of the NW device. In order to address issues associated with void formation, a technique was developed that removes Ni/Au contact metal films from the substrates to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN NW devices. This procedure determines the degree of adhesion of the contact films to the substrate and NWs and allows for the characterization of the morphology and composition of the contact interface with the substrate and nanowires. This technique is also useful for assessing the amount of residual contamination that remains from the NW suspension and from photolithographic processes on the NW-SiO2 surface prior to metal deposition. The detailed steps of this procedure are presented for the removal of annealed Ni/Au contacts to Mg-doped GaN NWs on a SiO2 substrate.

A technique was developed that removes Ni/Au contact metal films from their substrate to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN nanowire devices.

单氮化镓纳米线设备分析接触界面

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit  a strong degradation after annealing due to the  occurrence of void formation at the ...

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

This is an instructional paper to guide the construction and diagnostics of external cavity diode lasers (ECDLs), including component selection and optical alignment, as well as the basics of frequency reference spectroscopy and laser linewidth measurements for applications in the field of atomic physics.

外腔半导体激光器的原子物理的构建与鉴定

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

检测和钯的回收，从城市矿山黄金和钴金属使用标有纳米货车车轮形的孔隙新型传感器/吸附剂

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we demonstrate an optical spectroscopy method that is capable of resolving spectral features beyond that of the spin fine structure and homogeneous linewidth of single quantum dots (QDs) using a standard, easy-to-use spectrometer setup. This method incorporates both laser and photoluminescence spectroscopy, combining the advantage of laser line-width limited resolution with multi-channel photoluminescence detection. Such a scheme allows for considerable improvement of resolution over that of a common single-stage spectrometer. The method uses phonons to assist in the measurement of the photoluminescence of a single quantum dot after resonant excitation of its ground state transition. The phonon&#39;s energy difference allows one to separate and filter out the laser light exciting the quantum dot. An advantageous feature of this method is its straight forward integration into standard spectroscopy setups, which are accessible to most researchers.

The manuscript describes a method of phonon-assisted quasi-resonant fluorescence spectroscopy that incorporates both laser-limited resolution and photoluminescence (PL) spectroscopy. This method utilizes optical phonons to provide linewidth-limited resolution spectra of atom-like semiconductor structures in the energy domain. The method is also easily realized with a single spectrometer optical spectroscopy setup.

高分辨率声子辅助准共振荧光光谱仪

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we ...

Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples

The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. It consists of two magnetic measurement heads on both sides of the sample mounted on the legs of a u-shaped support. The sample is locally exposed to a magnetic excitation field consisting of two distinct frequencies, a stronger component at about 77 kHz and a weaker field at 61 Hz. The nonlinear magnetization characteristics of superparamagnetic particles give rise to the generation of intermodulation products. A selected sum-frequency component of the high and low frequency magnetic field incident on the magnetically nonlinear particles is recorded by a demodulation electronics. In contrast to a conventional MPI scanner, p-FMMD does not require the application of a strong magnetic field to the whole sample because mixing of the two frequencies occurs locally. Thus, the lateral dimensions of the sample are just limited by the scanning range and the supports. However, the sample height determines the spatial resolution. In the current setup it is limited to 2 mm. As examples, we present two 20 mm &#215; 25 mm p-FMMD images acquired from samples with 1 &#181;m diameter maghemite particles in silanol matrix and with 50 nm magnetite particles in aminosilane matrix. The results show that the novel MPI scanner can be applied for analysis of thin biological samples and for medical diagnostic purposes.

A scanner for imaging magnetic particles in planar samples was developed using the planar frequency mixing magnetic detection technique. The magnetic intermodulation product response from the nonlinear nonhysteretic magnetization of the particles is recorded upon a two-frequency excitation. It can be used to take 2D images of thin biological samples.

混频磁探测仪在平面样品成像磁性微粒

The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. ...

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 ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

采用部分氧化铝阴极增强电子注入和激子约束的纯蓝色量子点发光二极管

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...

Excitation-Scanning Hyperspectral Imaging Microscopy to Efficiently Discriminate Fluorescence Signals

Several techniques rely on detection of fluorescence signals to identify or study phenomena or to elucidate functions. Separation of these fluorescence signals were proven cumbersome until the advent of hyperspectral imaging, in which fluorescence sources can be separated from each other as well as from background signals and autofluorescence (given knowledge of their spectral signatures). However, traditional, emission-scanning hyperspectral imaging suffers from slow acquisition times and low signal-to-noise ratios due to the necessary filtering of both excitation and emission light. It has been previously shown that excitation-scanning hyperspectral imaging reduces the necessary acquisition time while simultaneously increasing the signal-to-noise ratio of acquired data. Using commercially available equipment, this protocol describes how to assemble, calibrate, and use an excitation-scanning hyperspectral imaging microscopy system for separation of signals from several fluorescence sources in a single sample. While highly applicable to microscopic imaging of cells and tissues, this technique may also be useful for any type of experiment utilizing fluorescence in which it is possible to vary excitation wavelengths, including but not limited to: chemical imaging, environmental applications, eye care, food science, forensic science, medical science, and mineralogy.

Spectral imaging has become a reliable solution for identification and separation of multiple fluorescence signals in a single sample and can readily distinguish signals of interest from background or autofluorescence. Excitation-scanning hyperspectral imaging improves on this technique by decreasing the necessary image acquisition time while simultaneously increasing the signal-to-noise ratio.

激发-扫描高光谱成像显微镜，以有效区分荧光信号

Several techniques rely on detection of fluorescence signals to identify or study phenomena or to elucidate functions. Separation of these fluorescence ...