Name: fabrication of nanopillar-based split ring resonators for displacement current mediated resonances in terahertz metamaterials
Uploaded: 2017-03-23T14:00:00.000+00:00
Duration: 10 min 28 s
Description: Watch this Scientific Journal Video about Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials at JoVE.com

这种材料是基于由明尼苏达双城大学的创业基金支持的工作。这项工作的部分以表征基金，明尼苏达州，通过MRSEC程序的NSF资助的材料研究设施网络（www.mrfn.org）的成员大学进行。这项工作的一部分也在其中通过NNCI程序从美国国家科学基金会获得部分支持明尼苏达纳米中心进行。

注意:几个在这些合成中使用的化学物质是有毒的，高度易燃，和触摸或吸入时可能引起刺激和严重的器官损伤。操作时，请佩戴适当的个人防护装备（PPE）。 1.金（Au）的纳米柱阵列的第一层（图2a-c和图2e-G）的制备<ol><li> 对Au电镀铜（Cu）籽晶层的制备（图2a，b和图2e中，f） <ol><li>使用4"高电阻率硅（Si）晶片。（电阻率:560 - 840Ω·cm）的作为基板的硅晶片是N型掺杂和抛光在一侧（ 图2a，电子 ）。 </li><li>切Si晶片成2厘米×2.5厘米的片，供以后使用。 </li><li>使用电子束（E-束）蒸发过程作为Si和铜之间的粘合层中的Si的样品沉积为5nm铬（Cr）层。 </li><li>上使用的现有的Cr层的顶部沉积10nm的Cu层电子束蒸发过程作为对Au电镀的种子层（ 图2b中，f）。 </li></ol></li><li> 电镀金纳米柱阵列（图2c，G） <ol><li> 构图纳米柱阵列 <ol><li>旋上2000转1.1节准备的60秒样本大衣光刻胶。 </li><li>烤样品在热板上在115℃下进行60秒。 </li><li>暴露与包含数千纳米柱图案为22号的Cr光掩模下的紫外线（UV）光致抗蚀剂-light（功率〜15毫瓦/厘米2）。 </li><li>与90秒搅拌开发商开发。 </li><li>冲洗用去离子（DI）水的样品并吹干用气枪样品。 </li></ol></li><li> 电镀金纳米柱阵列 <ol><li>在样品上，用丙酮去除光致抗蚀剂的顶部部分，以暴露用于电极连接的Cu籽晶层。 </li><li>连接SAMPLE（Cu籽晶层），使用的夹具和一个金属丝源计的负端。在这种情况下，所述样品是在电镀过程中的阳极。 </li><li>一块铂的连接（Pt）的涂覆的硅（大小相同样品）到源米的正端。铂是在电镀过程中的阴极。 </li><li>淹没都在金电镀液中Pt阴极和铜阳极。保持彼此面对的约1厘米的距离的两个电极。 </li><li>打开源表并在样品8分钟供应1.12五电镀Au的恒定电压（沉积速率:〜100纳米/分钟）。 </li><li>冲洗用DI水样品，随后用丙酮去除光致抗蚀剂。 </li><li>再次用去离子水清洗样品和吹干用气枪。 </li><li>检查在显微镜下电镀金纳米柱阵列。 </li><li>测量在Au纳米柱的厚度与轮廓（的厚度金奈米柱是〜800纳米）。 注:恒流的建立也可以用于电镀金纳米支柱。在这两个恒定电压和恒定电流的调校，用于金电镀提供了理想的电流和电压可以通过试验和错误来达到。 </li></ol></li></ol></li></ol> 2.创建金奈米柱之间的纳米间隙（图2d，H） <ol><li> Cr和Cu层的除去 <ol><li>浸没在铜蚀刻剂的样品，直到铜颜色消失。 </li><li>用去离子水清洗样品和吹干用气枪。 </li><li>检查在显微镜下坳奈米柱。 </li><li>淹没在Cr掩膜蚀刻剂样品10秒。 </li><li>用去离子水清洗样品和吹干用气枪。 </li><li>检查在显微镜下坳奈米柱。 </li></ol></li><li> 纳米级氧化铝的制备（ 的 Al 2 O 3）的差距 <ol><li>热火ALD系统湛BER至200℃。 </li><li>将样品在腔室的中心。 </li><li>腔室抽真空至真空并设置循环数为100（沉积速率:〜1埃/循环）。 </li><li>顺序和交替地脉冲三甲基铝（TMA）气体与0.015秒和水（H 2 O）蒸气与0.015秒的时间周期的时间周期到室中均匀地沉积在样品上的 Al 2 O 3层。每个脉冲之间的时间间隔为5秒。 TMA脉冲期间腔室压力是10乇和H 2 O蒸气脉冲期间的压力为2乇。 </li><li>清除和真空沉积的每个周期之间的腔。存款的 Al 2 O 3为100次循环，并采取了从腔室的样品。 </li><li>测量使用椭的的ALD 的 Al 2 O 3的厚度。 </li></ol></li></ol> 3.一种Au薄膜的第二层的制备（图2I-L和图2M-p）的<ol><li> 对Au电镀铜种子层的制备（图2I，米） <ol><li>将样品在电子束蒸发器样品架的中心。 </li><li>关闭在电子束蒸发器中的样品的旋转。 </li><li>在样品上沉积5nm的Cr层充当的 Al 2 O 3和Cu之间的粘合层。使用电子束蒸发过程中无样本轮换。 </li><li>沉积在使用电子束蒸发工艺没有样品旋转作为对Au电镀的籽晶层的现有的Cr层的顶部10纳米的Cu。 </li></ol></li><li> 电镀金薄膜（图2J，N） <ol><li>样品（Cu籽晶层）连接到使用一夹具和一导线的源计的负端子。在这种情况下，所述样品是在电镀过程中的阳极。 </li><li>铂阴极连接到源米的正端。 </li><li>淹没两个Pt阴极和Cu ANODE在金电镀液。保持彼此面对的约1厘米的距离的两个电极。 </li><li>打开源表并设置为1.35的恒定电压和在样本16分钟电镀Au等。 </li><li>用去离子水清洗样品和吹干用气枪。 </li><li>检查电镀Au及在显微镜下的预先电镀的Au纳米柱阵列。 </li><li>测量凹纳米柱的厚度与轮廓（在Au纳米柱的厚度为400〜纳米）。 注:向在Au电镀在节1.2.2类似的，恒流的建立也可用于电镀Au薄膜。在这两个恒定电压和恒定电流的调校，用于金电镀提供了理想的电流和电压可以通过试验和错误来达到。 </li></ol></li><li> 铬和铜层（图2K，O）的去除 <ol><li>淹没在铜蚀刻液样品10秒。 </li><li>用去离子水样本ð吹塑干燥用空气枪。 </li><li>检查在显微镜下坳奈米柱。 </li><li>淹没在Cr掩膜蚀刻剂样品10秒。 </li><li>用去离子水清洗样品和吹干用气枪。 </li><li>检查在显微镜下坳奈米柱。 注:另外，再次淹没在金电镀液样品去除铬和铜（步骤3.3）之后第二电镀Au层上淀积金额外的一层。这种额外的Au层增加了第二Au层的总厚度，并确保在Au层和Al 2 O 3层（ 图2I，p）的之间的良好接触。 </li></ol></li></ol> 4. C形SRR的定义（图2Q-S和图2U-W） <ol><li> 构图C形SRR（图2季度，U） <ol><li>旋涂层样品上的光致抗蚀剂以2000rpm进行60秒。 </li><li>在烤115℃热板样品60秒。 </li><l我&gt;暴露在UV光致抗蚀剂用光罩铬为22秒（的〜15毫瓦/ 平方厘米的功率）。 </li><li>与90秒搅拌开发商开发。 </li><li>用去离子水清洗样品和吹干用气枪样本。 </li></ol></li><li> 使用离子磨（图2R，V和图2S，w）的C形定义 <ol><li>附加上用双面铜导电带的离子磨样品架的样本。 </li><li>降温离子磨室6℃。 </li><li>离子磨为300伏的束电压和125毫安为〜30分钟的电子束电流的取样。 </li><li>取出样本，检查C形外的金奈米柱。 </li><li>重复步骤4.2.3和4.2.4如果金仍是C形外部可见。 </li><li>超声处理样品中的丙酮去除光致抗蚀剂。 </li><li>用去离子水清洗样品和吹干用气枪。 </li><li>检查在显微镜下的样品。 </li><li>重复步骤4.2.6和4.2。7，如果光致抗蚀剂没有完全去除。 注意:可替换地，适用于氧抗蚀软化步骤，将光致抗蚀剂去除光刻胶之前。然而，超声浴是，如果适用，除去光致抗蚀剂的最有效的方法。 </li></ol></li></ol> 5.罢免的 Al 2 O 3的空气纳米间隙（图2T，X） <ol><li>浸没在5％氟化氢（HF）溶液的样品进行5分钟，以除去的 Al 2 O 3。 </li><li>用去离子水清洗样品和吹干用气枪。 </li></ol>

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这种制造技术具有用于通过现有的方法，如电子束光刻和自组装产生纳米尺度结构显著优点。首先，纳米尺度的结构可以通过使用光掩模，具有纳米柱的阵列，这是不实际的用电子束光刻工艺的大面积（整个晶片）来实现。第二，在制造过程中使用传统的晶片规模微加工过程，这是更快，更简单，更便宜相比电子束光刻。第三，在原子尺度的纳米间隙可以容易地通过ALD工艺具有精确控制的特征尺?...

太赫兹超材料（MMS）已经开发了用于生物医学传感器和频率捷装置1，2，3，4，5，6，7，8，9，10，11。为了提高太赫兹的MM传感器的灵敏度和频率选择性，基于纳米柱分割环谐振器（SRR）已经使用金（Au）的内部产生位移电流纳米柱阵列以激发具有超高品质因子的THz共振（设计Q因数）（〜450）（ 图1）12。尽管基于纳米柱-的SRR表现出高Q值和有前途的传感能力，例如nanostructur制造具有高纵横比（大于40）和纳米尺度的间隙（子10毫微米）在大面积上ES仍然具有挑战性13。 最常用的技术来制造纳米级结构是电子束光刻（EBL）14，15，16，17。然而，EBL的分辨率仍然有限，由于光斑尺寸，电子散射，抗蚀性能，以及开发过程18，19。此外，它是不实际的制造使用EBL在大面积上的纳米结构，由于一个缓慢的过程的时间和大量处理费用20。以实现纳米结构的另一种策略是使用自组装技术21,22。通过在溶液中和util的自组装金属纳米立方体（NCS）定义静电作用和NC之间的聚合物配体的协会，组织良好的一维数组NC具有纳米级的差距可以达到23。纳米间隙的大小取决于纳米晶之间的聚合物配位体，并且可以通过具有不同分子量的24，25，26施加不同的聚合物材料来控制。自组装是实现可扩展性和成本效益的纳米结构23的强大技术。然而，相对于传统的微和纳米制造工艺的制造工艺比较复杂，和纳米间隙尺寸的控制不是用于电子设备的应用程序足够精确。为了成功地制造基于纳米柱-的SRR，一种新的制造方法应该被发明，实现以下目标:i）本制造工艺很容易申请，并与约定兼容人微纳米制造工艺; ⅱ）制造在大面积上是适用的; ⅲ）纳米间隙尺寸可以用0.1纳米的分辨率可容易且精确地控制，并且可以按比例缩小至10nm或更小。 一种新的制造方法是使用电镀工艺的组合和原子层沉积（ALD）工艺来制造基于纳米柱-的SRR证明。因为电镀是低成本的自填充过程中，它很容易制造的结构在大面积上。 ALD是一种可以通过在反应循环的过程中精确地控制的化学气相沉积（CVD）工艺。 ALD薄膜的分辨率可以是0.1纳米，该薄膜被均匀地涂覆有高的质量，这是合适的，以创建纳米尺度的间隙27，28。与10纳米间隙或更少，基于纳米柱-SRR阵列可以成功地制作在6毫米×6毫米的区域。既有Simulated和测量的太赫兹透射光谱显示出具有超高Q值和大频移，这证明通过位移电流介导的基于纳米柱，SRR的可行性共振行为。详细的制造方法是在协议部分如下所述，与视频协议可帮助从业者了解的制造过程，并避免与基于纳米柱-SRR的制造相关联的常见错误。

<table><tbody><tr><td>Silicon Wafer</td><td>Siltronic AG</td><td>N/A</td><td>100 mm diameter, N-type, one-side polish, resitivity: 560-840 &amp;Omega;&amp;bull;cm</td></tr><tr><td>Chromium</td><td>Kurt J. Lesker Company</td><td>EVMCR35J</td><td>99.95% pure</td></tr><tr><td>Copper</td><td>Kurt J. Lesker Company</td><td>EVMCU40QXQJ</td><td>99.99% pure</td></tr><tr><td>E-Beam Evaporator System</td><td>Rocky Mountain Vacuum Tech.</td><td>N/A</td><td>RME-2000</td></tr><tr><td>S1813 Positive Photoresist</td><td>Microposit</td><td>10018348</td><td>N/A</td></tr><tr><td>Spinner</td><td>Best Tools</td><td>S0114031123</td><td>SMART COATER 100</td></tr><tr><td>Mask Aligner</td><td>Midas</td><td>MDA-400LJ</td><td>N/A</td></tr><tr><td>Digital Hot Plate</td><td>Thermo Scientific</td><td>HP131725</td><td>Super-Nuvoa series, maximum temperature: 370 &amp;deg;C</td></tr><tr><td>MF319 Developer</td><td>Microposit</td><td>10018042</td><td>N/A</td></tr><tr><td>Acetone</td><td>Fisher Chemical</td><td>A18P-4</td><td>N/A</td></tr><tr><td>Isopropyl Alcohol</td><td>Fisher Chemical</td><td>A416-4</td><td>N/A</td></tr><tr><td>Gold 25 ES RTU</td><td>Technic Inc.</td><td>391427</td><td>N/A</td></tr><tr><td>Source Meter</td><td>Keithley</td><td>N/A</td><td>2612 System SourceMeter</td></tr><tr><td>Microscope</td><td>Omax</td><td>NJF-120A</td><td>N/A</td></tr><tr><td>Profilometer</td><td>Tencor Instruments</td><td>N/A</td><td>Alpha-Step 200</td></tr><tr><td>APS Copper Etchant 100</td><td>Transfene Company, Inc.</td><td>N/A</td><td>N/A</td></tr><tr><td>CE-5 M Chromium Mask Etchant</td><td>Transfene Company, Inc.</td><td>N/A</td><td>N/A</td></tr><tr><td>Atomic Layer Deposition System</td><td>Cambridge Nano Tech inc.</td><td>N/A</td><td>Savannah series</td></tr><tr><td>Ion Mill Etching System</td><td>Intlvac Thin Film</td><td>N/A</td><td>Nanoquest series</td></tr><tr><td>Ultrasonic Cleaner</td><td>Crest Ultrasonics</td><td>N/A</td><td>Powersonic series</td></tr><tr><td>Hydrofluoric Acid</td><td>Sigma-Aldrich</td><td>244279</td><td>Diluted to 5%</td></tr><tr><td>Field Emission Gun Scanning Electron Microscope</td><td>Jeol Ltd.</td><td>N/A</td><td>JEOL 6700 series</td></tr></tbody></table>

fabrication of nanopillar-based split ring resonators for displacement current mediated resonances in terahertz metamaterials

太赫兹裂环谐振器（SRR）超材料（MMS）已经研究了气体，化学和生物分子传感应用，因为SRR不受环境特性，如温度和压力围绕所述谐振器。在太赫兹频率的电磁辐射是生物相容的，这是一个重要的条件特别是对生物分子传感应用。然而，品质因子（Q因子）和传统薄膜基于开口环谐振器的频率响应（SRR）的MM是非常低的，这限制了它们的敏感性和选择性的传感器。在这项工作中，新的基于纳米柱-SRR彩信，利用位移电流，旨在提高Q因子高达450，它是围绕比传统的基于薄膜的MM的高出45倍。除了增强的Q因子，所述基于纳米柱-MMS诱导更大的频率偏移（相比于通过传统获得的移位17次人薄膜基于MMS）。因为显著增强Q因数和频率偏移以及生物相容的辐射的特性，该太赫兹基于纳米柱-SRR是具有高灵敏度和选择性的生物分子的传感器的发展理想的MM而不引起损坏或变形的生物材料。一种新的制造工艺已被证明是建立位移电流导太赫兹彩信基于纳米柱-的SRR。两步金（Au）的电镀处理和原子层沉积（ALD）工艺用于创建的Au纳米支柱之间的子10纳米尺度的间隙。由于ALD工艺是一个共形涂覆工艺，均匀的氧化铝（ 的 Al 2 O 3）的纳米级厚度层可以实现。通过顺序电镀另一个Au薄膜以填充的 Al 2 O 3和Au，密堆积的Au- 的 Al 2 O 3 -Au结构具有纳米级之间的空间中的 Al 2 O 3的差距可以是制造。纳米间隙的尺寸可以通过精确控制ALD工艺，其具有0.1纳米的准确度的沉积循环来明确界定。

<html>制造方案显示每个步骤（ 图2a-x）的 。光学图像（ 图2Y-AC）和扫描电子显微镜（SEM）图像（ 图2AD-AG），收集在不同制造步骤的基于纳米柱-的SRR。动画（ 图2a-c）示出电镀的Au纳米柱的第一层和电镀的Au膜的第二层以及它们之间产生的纳米间隙。 图2d示出了基于纳米柱-SRR的与两个的 Al 2 O <su...

Watch this Scientific Journal Video about Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials at JoVE.com

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

一个设计和一个新的基于纳米柱，开口环谐振器（SRR）的制造协议提出。

基于纳米柱裂环谐振器的研制为位移电流共振介导太赫兹超材料

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

fabrication-nanopillar-based-split-ring-resonators-for-displacement

Universidad San Sebastian

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Physics

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Unit 1

Electromagnetic Induction

SCIENTISTS IN ACTION

7.7K 次观看.  University of Minnesota. 一个设计和一个新的基于纳米柱，开口环谐振器（SRR）的制造协议提出。 

视频: Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

硅胶超高品质因子微谐振器的制造

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

科研

工程学

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

制造超材料使用光纤拉丝法

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic samples with a wide range of possible sensor designs such as interferometers and resonators 1,2. Most of the existing RI sensing applications focus on biological materials in aqueous solutions in visible and IR frequencies, such as DNA hybridization and genome sequencing. At terahertz frequencies, applications include quality control, monitoring of industrial processes and sensing and detection applications involving nonpolar materials.
Several potential designs for refractive index sensors in the terahertz regime exist, including photonic crystal waveguides 3, asymmetric split-ring resonators 4, and photonic band gap structures integrated into parallel-plate waveguides 5. Many of these designs are based on optical resonators such as rings or cavities. The resonant frequencies of these structures are dependent on the refractive index of the material in or around the resonator. By monitoring the shifts in resonant frequency the refractive index of a sample can be accurately measured and this in turn can be used to identify a material, monitor contamination or dilution, etc.
The sensor design we use here is based on a simple parallel-plate waveguide 6,7. A rectangular groove machined into one face acts as a resonant cavity (Figures 1 and 2). When terahertz radiation is coupled into the waveguide and propagates in the lowest-order transverse-electric (TE1) mode, the result is a single strong resonant feature with a tunable resonant frequency that is dependent on the geometry of the groove 6,8. This groove can be filled with nonpolar liquid microfluidic samples which cause a shift in the observed resonant frequency that depends on the amount of liquid in the groove and its refractive index 9.
Our technique has an advantage over other terahertz techniques in its simplicity, both in fabrication and implementation, since the procedure can be accomplished with standard laboratory equipment without the need for a clean room or any special fabrication or experimental techniques. It can also be easily expanded to multichannel operation by the incorporation of multiple grooves 10. In this video we will describe our complete experimental procedure, from the design of the sensor to the data analysis and determination of the sample refractive index.

The procedure for implementing a refractive index sensor for terahertz frequencies based on a grooved parallel-plate waveguide geometry is described here. The method yields a measurement of the refractive index of a small volume of liquid through monitoring of the shift in the resonant frequency of the waveguide structure

太赫兹微流控测量中的一个平行板波导传感器

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic ...

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

模拟，太赫兹超材料吸收器的制备与表征

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

基于微波光子系统回音壁模式谐振器

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

电浆光电导太赫兹发射器的设计，制造和实验表征

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Implementation of a Reference Interferometer for Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing its free spectral range (FSR), the module is put in parallel with a fiber taper-microcavity system and then calibrated through isolating and eliminating random shifts in the laser frequency (i.e. laser jitter noise). To realize the taper-microcavity junction and to maximize the optical power that is transferred to the resonator, a single-mode optical fiber waveguide is pulled. Solutions containing polystyrene nanobeads are then prepared and flown to the microcavity in order to demonstrate the system&#8217;s ability to sense binding to the surface of the microcavity. Data is post-processed via adaptive curve fitting, which allows for high-resolution measurements of the quality factor as well as the plotting of time-dependent parameters, such as resonant wavelength and split frequency shifts. By carefully inspecting steps in the time-domain response and shifting in the frequency-domain response, this instrument can quantify discrete binding events.

A reference interferometer technique, which is designed to remove undesirable laser jitter noise for nanodetection, is utilized for probing an ultra-high quality factor microcavity. Instructions for assembly, setup, and data acquisition are provided, alongside the measurement process for specifying the cavity quality factor.

一个参考干涉仪的Nanodetection实施

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing ...

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

生物工程

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

制备与表征超导谐振器的

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

1-D光子晶体空穴对纳米纤维使用飞秒激光诱导消融制造

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...