Thanks to Michael Knutson, Paul Hamric, Greg Scott, and Chris Landes for helpful discussions and assistance related to the custom inert atmosphere sample holder and assistance in the University of Utah student machine shop. P.C. acknowledges the NSF GRFP under Grant No. 0750758. P.C. acknowledges the University of Utah Nanotechnology Training Fellowship. R.M. acknowledges a NSF CAREER Award No. 1054899 and funding from the USTAR Initiative.

注:执行下洁净室100级条件或更好以下所有步骤。 1.样品制备<ol><li>清理"直径2硅片缓冲氧化物刻蚀（BOE）解决方案（6部分40％NH 4 F和1份49％HF）2分钟（ 注意:危险化学品 ）。选择这种蚀刻时间以除去任何有机物或污染物的表面上。冲洗以去离子（DI）水中约5分钟。干燥晶片用干燥的N 2。 注意:不要使用HF时单独工作。总是戴着眼睛的保护，以防泄漏防护面罩和个人防护装备（PPE）。帖子准则在哪里进行蚀刻在实验室中使用和处理的HF浪费。 注意:步骤1.2至1.7仅用于电化学锁定 。如果执行通过溶解锁定进行第2步。 </li><li>放下工作电极，溅射铂（Pt）为100纳米到干净的2"直径的硅酸在晶圆。 </li><li>前蚀刻铂薄膜，清理从以前的干蚀刻任何杂质或剩余的光刻胶RIE室。 </li><li>抽空该室，直至1×10 -5乇达到基本压力。确保RF功率设置为200瓦，并且流速为氧气和氩气分别设置在50sccm和10sccm的。点燃的Ar / O 2等离子和运行至少1小时。 </li><li>关闭的Ar / O 2等离子体，并允许该腔室泄为大约10分钟。 </li><li>蚀刻铂薄膜表面，加载样品放入RIE室和向下泵送腔室以1×10 -5乇的基础压力。这个时间设定氩流量为0标准立方厘米。点燃O 2等离子，让这个过程运行30分钟。 </li><li>关闭的O 2等离子体，并让该室通风口10分钟。 </li></ol>光致变色分子使用自定义L 2.热蒸发流温度蒸发器（LTE）的<ol><li>填写ALO 2船BTE 30毫克，并加载到自定义的LTE源（ 图6）。 </li><li>装载硅片到样品安装。 </li><li>密封室端口和泵室下降到1×10 -6乇的基础压力。 </li><li>蒸发BTE在100℃的设定温度，以30nm的膜厚度。 </li><li>立即蒸发后，洪水照射样品以5分钟的UV改造BTE材料的封闭形式，1c上 。 </li><li>为了确定样本大小，切割的小片，使用金刚石划线划伤从硅表面的边缘的线的晶片。抢在划痕线两侧的晶片和弯曲晶片向下直至其断裂沿着晶体平面。 </li><li>执行验证BTE薄膜厚度轮廓测量。要做到这一点，从头开始用细边镊子样品。测量阶梯高度来回米此划痕，它是在左，右光标位置之间的高度差。 注:在薄膜厚度不准确将导致在曝光剂量差异。 </li><li>在N 2充满手套箱店内剩余的样品。 </li></ol> 3.曝光注:执行惰性气氛条件下，所有的风险敞口，以防止样品降解。 <ol><li>按照相同的步骤，在步骤2.6中概述裂解样品。 </li><li>在惰性气体样品架上加载样品。 </li><li>安装惰性样品架在舞台上。吹扫样品用N 2。 </li><li>利用干涉仪，将样品以期望的曝光时间暴露，如在图8中所示的那个。 </li></ol> 4.电化学氧化法三电极电池注:在惰性气氛的条件下进行电化学防止样品降解。 <ol><li>钳上热板的顶部上的干净的玻璃小瓶中。放置在小瓶一个清洁的搅拌棒。开启搅拌器。 </li><li>清洁新的铜剪辑甲醇。用甲醇清洗铂反电极。 </li><li>使用干净的铜夹，通过在特氟纶小瓶帽上的孔中的一个剪辑的样本。确保夹在只露出铂。 </li><li>把铁氟龙瓶盖到小瓶。夹在红色导线到铂电极和石墨到铜夹子拿着样品。 </li><li>使用干净的注射器，通过在特氟纶瓶盖第二孔填充用过滤的去离子（DI）水的小瓶中。作为填充不高对样品浸泡任何裸露的铂。 </li><li>通过水3-5分钟气泡的氮。关掉氮气。 </li><li>将参考电极在特氟隆瓶盖的第二个孔。剪辑铅白到参考电极。检查以确保无裸露铂邻n个样品浸入。 </li><li>用伏安，将氧化电压为0.5 V /秒。 </li><li>后所需要的氧化时间已经过去时，打开电源向伏安关闭。 </li><li>从铂反电极，铜夹，和参考电极取出红色，黑色，白色和剪辑。 </li><li>暴露样品于紫外线5分钟。 </li></ol> 5.样品开发-电化学锁定 注:在惰性气氛的条件下进行显影，以防止样品降解。 <ol><li>开发在过滤5（重量％）的异丙醇样品，95（重量％）乙二醇的时间的所需量。注意:通常为50nm的样品被开发为30-60秒，而为80nm的样品为60-180秒开发的。 </li><li>用干N 2干燥的样品。 </li><li>立即暴露样品到5分钟的紫外线。 </li></ol> 6.样品开发-溶解锁定 </eM&gt; 注:在惰性气氛的条件下进行显影，以防止样品降解。 <ol><li>在一个干净的玻璃烧杯用100毫升乙二醇中，开发所需的开发时间的暴露试料。 </li><li>用干N 2干燥的样品。立即暴露样品到5分钟的紫外线。 </li></ol> 7.多重曝光<ol><li>如果执行多次曝光重复步骤3-6具有相对于光学器件的样品的译文。 </li></ol>

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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beam+pen+lithography.">Beam pen lithography.</a> Nature Nanotechnology. 5, 637-640 (2010).</li><li>Xie, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manipulating+spatial+light+fields+for+micro-+and+nano-photonics.">Manipulating spatial light fields for micro- and nano-photonics.</a> Physica E: Low-dimensional Systems and Nanostructures. 44, 1109-1126 (2012).</li><li>Leroy, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-speed+metal-insulator+transition+in+vanadium+dioxide+films+induced+by+an+electrical+pulsed+voltage+over+nano-gap+electrodes.">High-speed metal-insulator transition in vanadium dioxide films induced by an electrical pulsed voltage over nano-gap electrodes.</a> Applied Physics Letters. 100 (21), 213507 (2012).</li><li>Carr, D., Sekaric, L., Craighead, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+nanomechanical+resonant+structures+in+single-crystal+silicon.">Measurement of nanomechanical resonant structures in single-crystal silicon.</a> Journal of Vacuum Science &amp; Technology B. 16 (6), 3821-3824 (1998).</li><li>Wilhelmi, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+prototyping+of+nanostructured+materials+with+a+focused+ion+beam.">Rapid prototyping of nanostructured materials with a focused ion beam.</a> Japanese Journal of Applied Physics. 47 (6), 2010-5014 (2008).</li><li>Hell, S. 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The authors have nothing to disclose.

The fabrication, experimental setup and related operational procedures of Patterning via Optical Saturable Transitions (POST) have been described. By exploiting the linear switching properties of thermally stable photochromic molecules, POST offers new perspectives on circumventing the far-field diffraction limit.1-2,4
Previously long-term storage requirement of the samples was solved by storing the samples under N2, directly after the initial evaporation.2 However, the significant line-edge roughness evident in the gratings, Figures 3 and 5, is likely due to the formation of oxidized products of 1c in the presence of air.2 Improving the uniformity of the patterns requires that the exposure and development process be conducted under an inert atmosphere. To address the exposures done in ambient conditions, a custom inert atmosphere sample holder was designed and fabricated. The sample holder needed to provide a rigorous inert gas blanketing of the air-sensitive BTE in closed form, 1c and maintain an excellent seal for sufficient time to obtain the appropriate exposure conditions. The holder was configured so that it could be easily modified for various optical configurations.
One way to address the exposure of the sample to atmosphere would be to design and fabricate an in-situ setup. The main goal of in-situ experimentation in both the electrochemical and dissolution method is performing the exposure, electrochemical oxidation, and development in an O2 purged environment. Having the experiments performed in-situ would aid in the yield and quality of the desired nanostructures.
Currently the extension of this super-resolution technique, POST, to 3-dimensions, which would provide a promising approach to nanofabrication of nanoporous scaffolds, which act as supports for the initial cell attachment and subsequent tissue formation in biological tissue engineering (TE) is being investigated. The nanolithographic technique used to fabricate these initial scaffolds must produce a high yield and be at a low cost in order to produce any significant impact.14
There are, however, some limitations to the POST technique. The need for a separate locking mechanism (electrochemical or dissolution) requires an immersion-type setup. This could add associated complexities and cost if performed in-situ. Also, the need for a platinum layer for the electrochemical locking step (see Step 1.2) might preclude some already patterned substrates or devices. The organic compound (BTE), which is used as the recording medium, requires a relatively complex synthesis, which may add to the cost of the technique initially. However, with increased volumes, the cost should decrease.

光学光刻是具有关键的重要性在纳米级的结构和设备的制造。在新的光刻技术的进步提高了能力，使新的一代新型设备8-11在这篇文章中，回顾，提出一类是取得使用新型的光开关分子深亚波长光学分辨率的光刻技术。这种方法被称为经光学-饱和转换（POST）图案。1-3 POST是独特地结合的饱和光致变色分子的光转换，具体地（1,2-双（5,5&#39;-二甲基-2,2&#39;- bithiophen基））的想法一新颖的纳米加工技术perfluorocyclopent -1-烯。通俗地，该化合物被称为BTE， 图1中 ，例如在受激发射损耗（STED）显微镜12使用时，与干涉光刻，这使得它的强大工具LARG深亚波长特征的e-区域并行纳米图案上的各种潜在扩展表面的至2-和3-维。 光致变色层最初是在一个均匀的状态。当该层暴露于λ1的均匀的照明，将其转换成所述第二异构态（1c）中 ， 图2，然后将样品在λ2，其中样品进入所述第一异构态（转换暴露于聚焦节点1O）无处不在，除了在节点的酒店附近。通过控制曝光剂量，未转化的区域的尺寸可以被任意小。异构体中的一个的后续定影步骤可以选择性地和不可逆变换（锁定）到第三状态（黑色）以锁定模式。接着，对层被均匀地暴露于λ1，它转换以外的所有锁定区域恢复到原来的状态。该的步骤顺序可以重复与相对于光学样品的位移，导致2锁定区域的间隔比所述远场衍射极限小。因此，任意的几何形状可被图案化在一个"点阵"时尚1-3

<table><tbody><tr><td>Isopropanol</td><td>Fisher Scientific</td><td>P/7500/15</td><td>CAUTION: flammable, use good ventilation and avoid all ignition sources.</td></tr><tr><td>Buffered Oxide Etch</td><td></td><td></td><td></td></tr><tr><td>Methanol</td><td>Ricca Chemical</td><td>48-293-2&amp;nbsp;</td><td>CAUTION: flammable, use good ventilation and avoid all ignition sources.</td></tr><tr><td>Ethylene Glycol</td><td>Sigma-Aldrich</td><td>324558</td><td>CAUTION: Harmful if swallowed</td></tr><tr><td>Silicon wafer</td><td></td><td></td><td></td></tr><tr><td>Diamond Scribe</td><td></td><td></td><td></td></tr><tr><td>Glass Beakers</td><td></td><td></td><td></td></tr><tr><td>Tweezers</td><td>Ted Pella</td><td>5226</td><td></td></tr><tr><td>Reactive Ion Etching System</td><td>Oxford</td><td>Plasma Lab 80 Plus</td><td></td></tr><tr><td>Inert Atmosphere Sample Holder</td><td>Proprietary In-house Designed</td><td></td><td></td></tr><tr><td>Polarizing beamsplitter cube</td><td>Thorlabs</td><td>PBS052</td><td></td></tr><tr><td>HeNe Laser</td><td>Melles Griot</td><td>25-LHP-171</td><td>CAUTION: Wear safety glasses</td></tr><tr><td>Half-wave plates</td><td>Thorlabs</td><td>WPH05M-633</td><td></td></tr><tr><td>Thermal Evaporator</td><td>Proprietary In-house Designed</td><td></td><td></td></tr><tr><td>TMV Super</td><td>TM Vacuum Products</td><td>TMV Super</td><td></td></tr><tr><td>Voltammograph</td><td>Bioanalytical Systems</td><td>CV-37</td><td></td></tr><tr><td>Shortwave UV lamp 365&amp;nbsp;nm</td><td>UVP Analytik Jena Company</td><td>UVGL-25</td><td>CAUTION: Wear UV safety glasses</td></tr></tbody></table>

patterning via optical saturable transitions - fabrication and characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

制作样品: 不同的氧化时间被表征为在0.85 V的循环伏安法测定的氧化电压在图3所示的原子力显微镜照片。的50纳米厚的薄膜暴露于0.95毫瓦/ cm 2的功率密度的驻波在周期为400nmλ= 647毫微米为60秒。作为氧化时间从10分钟增加到25分钟，可以清楚地看到的对比度的损失，因为一些由1O的地区得到氧化为好。显影剂（5（重量％）的异丙醇:95（重量％）乙二醇）溶解所有氧化部分。较大的氧化时间导致不均匀线，增加了表面的不均匀性发展之后。因此，仔细选择的氧化条件是图案形成高质量的纳米结构的关键。2 闭合形式的较高偶极矩分子，1c的相比，开放形式，1O，允许闭合形式更可溶于极性溶剂。这被表示在图4中，其中半数的样品被转化为封闭的形式，1c和另一半被转化为开放的形式，1O。然后将样品开发100（重量％）乙二醇为几个不同的开发时间，然后将膜的厚度其余是使用轮廓仪测得的。从该曲线图中的溶解锁定步骤的高选择性看出。以除去封闭形式，1c中，作为用于纳米压印光刻可用于反应离子蚀刻（RIE）工艺的残留层13 由于光致变色膜可以容易地恢复到在暴露于UV原来的状态，这是很简单的想法延伸到多重曝光。这是，当然，需要用于创建密集模式。这里，这种方法的可行性，示出通过执行相同的驻波的两次曝光，但与在（ 图5）之间的〜45度的旋转。每个曝光进行对Lloyd&#39;s镜干涉仪，具有一个驻波周期，540纳米在λ= 647纳米（入射强度〜2.1毫瓦/厘米2）1分钟。第一曝光后，将样品浸渍在100（重量％）乙二醇30分钟，并暴露于短波长紫外灯进行5分钟的分子转换成原来的闭环异构体1c上 。然后将样品旋转大约45°的相对于光学，并进行第二次曝光的驻波。再次，将样品浸渍在100（重量％）乙二醇30分钟。每个显影后，将样品用去离子水清洗，并用N 2干燥。相应的原子力显微照片解析与间距小行作为〜260纳米或＆＃955; /2.5，这是不到一半的驻波的期限为3。 为了验证样品架的功效，几个曝光进行，以查看是否该线边缘粗糙度得到了改善。假设入射正弦照明，将所得的特征尺寸，可以很容易地进行模拟。在图7中 ，此特征尺寸被绘制为的曝光时间使用蓝色实线的功能。实验测得的值是利用杂交示。使用浓淡阈值作为唯一的拟合参数，它表明，这个简单的模型能准确地解释我们的实验结果。最小的实验获得的特征尺寸为〜85纳米，对应于〜λ/ 7.4的线宽。的曝光时间更精确的控制应该使更小的特征。注意，作为曝光时间的增加，模拟结果表明，特征尺寸应该减小显著下面的远场衍射利麻省理工学院。从扫描电子显微镜（SEM）图像，示出了线边缘粗糙度与使用惰性气氛样本保持器的改进。 <img alt="图1" src="/files/ftp_upload/52449/52449fig1highres.jpg" /> 图1.有机光致变色分子结构。化合物1存在于开放的形式，1O和封闭的形式，1C。电化学氧化选择性转换1c至的10X。 <img alt="图2" src="/files/ftp_upload/52449/52449fig2highres.jpg" /> 图2. POST技术。曝光和构图"锁定"需要录制功能的步骤。 （A）电化学氧化。 （B）溶解1 photoisomer的。 图3.隔离功能。开发后线样品在不同氧化时间的原子力显微照片。的〜50纳米2薄膜厚度。转载自[坎，P.， 等权限。光致变色二芳基乙烯膜的亚波长纳米图案。 应用程序。物理学。快报 。100（18），183103]。版权所有[2012]，AIP出版社有限责任公司。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52449/52449fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/52449/52449fig4highres.jpg" /> 图4.溶出速率。该图表示1c的100（重量％）的宏观尺度的溶解性和1O EthylenË乙二醇。对〜29 nm的3薄膜厚度。转载自[坎，P.， 等权限。通过一个photoisomer。 应用选择性溶解二芳基乙烯膜的纳米图案。物理学。快报 。103（17）173112。版权所有[2013]，AIP出版社有限责任公司。 <img alt="图5" src="/files/ftp_upload/52449/52449fig5highres.jpg" /> 双重曝光图5.实验示范左:。样品使用POST双重曝光的示意图，显示方向右:产生模式的原子力显微照片。原子力显微照片揭示了特征为〜260nm处，这大约是照明驻波的半周期之间的最小间距。3重印从[坎，P。， 等人的许可。通过选择性disso二芳基乙烯膜的纳米图案1 photoisomer的（分辨率）。 应用。物理学。快报 。103（17）173112。版权所有[2013]，AIP出版社有限责任公司。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52449/52449fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图6" src="/files/ftp_upload/52449/52449fig6highres.jpg" /> 图6.自蒸发器中。在POST方法中使用的低温热蒸发器（LTE）的图像。2重印从[坎，P。， 等人的许可。光致变色二芳基乙烯膜的亚波长纳米图案。 应用程序。物理学。快报 。100（18），183103]。版权所有[2012]，AIP出版社有限责任公司。 <img alt="图7" src="/files/ftp_upload/52449/52449fig7highres.jpg" /> 图7.线宽VS曝光时间为单个发展吨和曝光。事件模拟正弦照明被示为蓝色实线，而实验数据是使用杂交示。正弦照明用的457纳米的阶段是假设。插图:SEM图像<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52449/52449fig7large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图8" src="/files/ftp_upload/52449/52449fig8highres.jpg" /> 图8.示意图用于曝光的马赫-策德尔干涉设置的，第一半波片，用于控制在每个臂的功率。第二半波片，用于控制偏振。

Watch this Scientific Journal Video about Patterning via Optical Saturable Transitions - Fabrication and Characterization at JoVE.com

Patterning via Optical Saturable Transitions - Fabrication and Characterization

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

通过光学吸收跃迁图案 - 制备与表征

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

patterning-via-optical-saturable-transitions-fabrication

Nanyang Technological University

Research

JoVE Journal

Engineering

6.8K 次观看.  The University of Utah. We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

视频: Patterning via Optical Saturable Transitions - Fabrication and Characterization

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view and for its considerable potential for practical applications. Slow light photonic crystal waveguides, in particular, have played a major part and have been successfully employed for delaying optical signals1-4 and the enhancement of both linear5-7 and nonlinear devices.8-11
Photonic crystal cavities achieve similar effects to that of slow light waveguides, but over a reduced band-width. These cavities offer high Q-factor/volume ratio, for the realization of optically12 and electrically13 pumped ultra-low threshold lasers and the enhancement of nonlinear effects.14-16 Furthermore, passive filters17 and modulators18-19 have been demonstrated, exhibiting ultra-narrow line-width, high free-spectral range and record values of low energy consumption.
To attain these exciting results, a robust repeatable fabrication protocol must be developed. In this paper we take an in-depth look at our fabrication protocol which employs electron-beam lithography for the definition of photonic crystal patterns and uses wet and dry etching techniques. Our optimised fabrication recipe results in photonic crystals that do not suffer from vertical asymmetry and exhibit very good edge-wall roughness. We discuss the results of varying the etching parameters and the detrimental effects that they can have on a device, leading to a diagnostic route that can be taken to identify and eliminate similar issues.
The key to evaluating slow light waveguides is the passive characterization of transmission and group index spectra. Various methods have been reported, most notably resolving the Fabry-Perot fringes of the transmission spectrum20-21 and interferometric techniques.22-25 Here, we describe a direct, broadband measurement technique combining spectral interferometry with Fourier transform analysis.26 Our method stands out for its simplicity and power, as we can characterise a bare photonic crystal with access waveguides, without need for on-chip interference components, and the setup only consists of a Mach-Zehnder interferometer, with no need for moving parts and delay scans.
When characterising photonic crystal cavities, techniques involving internal sources21 or external waveguides directly coupled to the cavity27 impact on the performance of the cavity itself, thereby distorting the measurement. Here, we describe a novel and non-intrusive technique that makes use of a cross-polarised probe beam and is known as resonant scattering (RS), where the probe is coupled out-of plane into the cavity through an objective. The technique was first demonstrated by McCutcheon et al.28 and further developed by Galli et al.29

Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).

光子晶体慢光波导和腔体的制备与表征

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view ...

科研

工程学

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

无序横向安德森本地化光聚合物光纤的制备和表征

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems3. We focus here on the use of a continuous-wave optical parametric oscillator3,4. This system is based on a non-linear &#967;2 crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. 
Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states5. Generating directly such states is a difficult task and would require strong &#967;3 non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

We describe the reliable generation of non-Gaussian states of traveling optical fields, including single-photon states and coherent state superpositions, using a conditional preparation method operated on the non-classical light emitted by optical parametric oscillators. Type-I and type-II phase-matched oscillators are considered and common procedures, such as the required frequency filtering or the high-efficiency quantum state characterization by homodyning, are detailed.

光与连续波光学参量振荡器的量子态工程

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

制造和微流控光机振荡器测试

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues.  In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates.  The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them protein and cell resistive.  Presence of insulating PEG molecules on the electrode surface was verified by cyclic voltammetry employing potassium ferricyanide as a redox reporter molecule.  Importantly, the application of reductive potential caused desorption of the PEG layer, resulting in regeneration of the conductive electrode surface and appearance of typical ferricyanide redox peaks.    Application of reductive potential also corresponded to switching of ITO electrode properties from cell non-adhesive to cell-adhesive. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.  Micropatterning of several cell types was demonstrated on these substrates.   In the future, the control of the biointerfacial properties afforded by this method will allow to engineer cellular microenvironments through the assembly of three or more cell types into a precise geometric configuration on an optically transparent substrate.

Non-fouling PEG silane monolayer was desorbed from individually addressable ITO electrodes on glass by application of a reductive potential. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.

在光学透明的铟锡氧化物电极的图案细胞

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular ...

生物学

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

一个纳米光输送带的制作和操作

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Cell Patterning on Photolithographically Defined 
Parylene-C: SiO2 Substrates

Cell patterning platforms support broad research goals, such as construction of predefined in vitro neuronal networks and the exploration of certain central aspects of cellular physiology. To easily combine cell patterning with Multi-Electrode Arrays (MEAs) and silicon-based &#8216;lab on a chip&#8217; technologies, a microfabrication-compatible protocol is required. We describe a method that utilizes deposition of the polymer parylene-C on SiO2&#160;wafers. Photolithography enables accurate and reliable patterning of parylene-C at micron-level resolution. Subsequent activation by immersion in fetal bovine serum (or another specific activation solution) results in a substrate in which cultured cells adhere to, or are repulsed by, parylene or SiO2 regions respectively. This technique has allowed patterning of a broad range of cell types (including primary murine hippocampal cells, HEK 293 cell line, human neuron-like teratocarcinoma cell line, primary murine cerebellar granule cells, and primary human glioma-derived stem-like cells). Interestingly, however, the platform is not universal; reflecting the importance of cell-specific adhesion molecules. This cell patterning process is cost effective, reliable, and importantly can be incorporated into standard microfabrication (chip manufacturing) protocols, paving the way for integration of microelectronic technology.

Cell Patterning on Photolithographically Defined 
Parylene-C: SiO2 Substrates

This protocol describes a microfabrication-compatible method for cell patterning on SiO2. A predefined parylene-C design is photolithographically printed on SiO2 wafers. Following incubation with serum (or other activation solution) cells adhere specifically to (and grow according to the conformity of) underlying parylene-C, whilst being repulsed by SiO2 regions.

在光刻技术定义的聚对二甲苯-C细胞图案：二氧化硅<sub&gt; 2</sub&gt;基板

Cell patterning platforms support broad research goals, such as construction of predefined in vitro neuronal networks and the exploration of certain ...

生物工程

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 ...

Rapid Repetition Rate Fluctuation Measurement of Soliton Crystals in a Microresonator

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the nonlinearity in a propagation Kerr medium. The development of dissipative Kerr solitons (DKSs) in high-Q microcavities drives a novel, compact, chip-scale soliton source. When DKSs serve as femtosecond pulses, the repetition rate fluctuation can be applied to ultrahigh precision metrology, high-speed optical sampling, and optical clocks, etc. In this paper, the rapid repetition rate fluctuation of soliton crystals (SCs), a special state of DKSs where particle-like solitons are tightly packed and fully occupy a resonator, is measured based on the well-known delayed self-heterodyne method. The SCs are generated using a thermal-controlled method. The pump is a frequency fixed laser with a linewidth of 100 Hz. The integral time in frequency fluctuation measurements is controlled by the length of the delay fiber. For a SC with a single vacancy, the repetition rate fluctuations are ~53.24 Hz within 10 &#181;s and ~509.32 Hz within 125 &#181;s, respectively.

Here, we present a protocol to generate soliton crystals in a butterfly-packaged micro-ring resonator using a thermal tuned method. Further, the repetition rate fluctuations of a soliton crystal with a single vacancy are measured using a delayed self-heterodyne method.

微谐振器中孤子晶体的快速重复率波动测量

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

使用多色荧光检测液滴微流控光纤

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...