这项工作是部分地在康奈尔大学纳米科学与技术基金，国家纳米技术基础设施网络的成员，这是由美国国家科学基金会（ECCS格兰特-1542081）支持执行。我们承认从美国空军研究实验室（AFRL）这项工作的支持。这种材料是基于由下奖号ECCS14052481美国国家科学基金会部分支持工作。

注:此协议假定光子芯片已经制造。这里所描述的芯片（在图1A中示出）使用用于硅光子器件11标准加工技术在康奈尔大学纳米科技设施制造。这些方法包括使用硅绝缘体上硅片（220 nm厚的硅层构成的，二氧化硅的3-μm的层，和一个525微米厚的硅衬底），电子束光刻，以限定条波导（500纳米范围内），和二氧化硅包层（〜3微米厚）的等离子体增强化学气相沉积。微环谐振器在设计时的18.5微米内半径和150nm的波导至环形间隙。优点对于本装置的数字包括损失，品质因数，自由光谱范围，和分散。 1.光子芯片的制备<ol><li>放置一个小的Amoun蜡在对横截面抛光安装吨并加热到〜130℃。 注:蜡的使用量取决于安装在所述样本的尺寸。必须有足够的蜡，以保持芯片不动，而过多会导致在芯片方面蜡。 </li><li>放置在抛光的部分中的光子芯片与蜡装入。确保使芯片是对所述安装平面将蜡完全熔化。处理芯片时要避免损坏方面使用塑料镊子。 </li><li>允许安装在周围空气中冷却，使蜡凝固。冷却比这更快可能导致芯片的损坏。 </li><li>抛光的芯片方面。 注:选择正确的磨削垫与垫是过于激进可导致抛光远超出期望的芯片的开始是很重要的。 <ol><li>附加抛光安装到抛光机和抛光只有几秒钟。带有3微米的粗糙度甲垫已被证明是一个很好的起点为硅芯片具有约1cm小面的长度。 </li><li>取出抛光安装和检查芯片方面，以确定该芯片是如何安装的水平。 注:显微镜是用于测量波导的端部与所述芯片的小面之间的距离是有用的。这些测量允许小面和要确定的波导之间的角度。 </li><li>请以提高芯片的流平性，以在抛光机上的微米必要的调整。 </li><li>重复步骤1.4.1-1.4.3直到芯片的端面和波导内的是相互正交的0.15°。 </li><li>波兰在〜50μm时，检查每个步骤之间的芯片，以监视剩余的距离，直到有〜100微米的步骤芯片左抛光。如果在任何点处的包层似乎是从该表面剥离，确保垫作为抛光从芯片的底部的顶部旋转如此。 注意:这也可能有助于使用抛光润滑剂代替水。这是分层的包层应力的结果，并且是在制造过程需要优化的指示。 </li><li>改变为1微米的研磨垫和抛光，直到有〜20μm的余留。 </li><li>改变为0.5微米的衬垫，并继续研磨另外15微米。 </li><li>使用的最终5μm的0.1μm的垫，以确保平稳的方面。硅光子芯片的研磨前后的小面的显微镜图像示于图2。 </li></ol></li><li>加热的安装与连接的芯片至〜130℃，以使蜡熔化。 </li><li>一旦蜡完全融化，取出从安装芯片，让它慢慢冷却。 </li><li>清洁任何使用丙酮，异丙醇，和水的芯片的剩余蜡。 </li></ol> 2.光纤尾纤的制备<ol><li>剥去任何缓冲或涂层FROM单模光纤（SMF）尾纤的端部和从超高数值孔径（娜）光纤的一端。 </li><li>清洁纤维的裸露端用丙酮和甲醇的混合物中。 </li><li>切割两条光纤的裸露端与商用光纤切割。 </li><li>熔接纤维的切割端。一种用于拼接SMF到娜纤维配方示于表1中 。 </li><li>在拼接滑动的保护套，并放置在该套筒烘箱永久其附加到纤维。 </li><li>重复步骤2.1-2.5中以制备总共三个纤维。 </li></ol> 3.测试设置的配置注意:测试设置的图示于图1B。安装件用于芯片是铜基座，其与一个热电冷却器（TEC）相接触。有装配有可见光和红外（IR）摄像机用于观察所述光子芯片的显微镜。 <ol><li>地点安装蜡的芯片上的小量和施加电压到TEC以熔化蜡。 </li><li>放置在熔化的蜡片，确保其在山上坐平。 </li><li>取下TEC电压和允许安装和芯片慢慢冷却。 </li><li>各拼接纤维的重视与聚酰亚胺带的纤维V形槽和安装单个V形槽的每个使用制造商提供的安装硬件的3轴级。 </li><li>光纤边缘耦合。 <ol><li>三个纤维连接到它们各自的部件:一个激光器的光输出，另两个光功率米。 </li><li>调整显微镜，使其聚焦在波导到达边缘的芯片上。 </li><li>靠近芯片边缘的纤维，使得它们在可见光相机的视点位置，并调整它们的高度，使得每个纤维的芯处于焦点。 </li><li>调整纤维的水平定位与阶段micrometeRS使他们一字排开与波导。 </li><li>打开激光和调整所述输入光纤的水平和垂直位置的千分尺，直到光被耦合到所述波导的光输出。这将显示红外线摄像机沿输入波导散射上。 </li><li>调谐激光器的波长到其中微环形谐振腔被点亮的相机上的点。这表明谐振条件被满足并且该光在到达输出波导。 </li><li>调整输出纤维的水平和垂直位置微米直到存在来自波导的功率表延伸的光的可测量的量。 </li><li>通过操纵三种纤维的水平和垂直位置微米最大化功率到两个检测器。 </li><li>通过使用压电控制研究进行精细调整时的水平和垂直位置的纤维进一步最大化的电源检测器ERS。 </li><li>使用压电控制器移动纤维稍微靠近芯片。确保不使用微米的纤维推到芯片上，因为这样做可能会破坏纤维的切开端。 </li><li>重复步骤3.5.9和3.5.10，直到纤维对芯片的两侧紧压。 注意:从波导，加上波导传输差过度散射光，可以是波导缺陷的指示。这些可以包括，但不限于，材料缺陷位点，拼接边界，和过度的波导粗糙度。 </li></ol></li><li>放置激光器和所述芯片之间的基于光纤的偏振控制器。这允许，它使向芯片的偏振状态的控制。波导，作为较宽的大于高度，有助于最小化任何片上的偏振旋转。 </li><li>色散特性。 <ol><li>调谐激光器输出的偏振以最大化耦合到<html>该芯片。该装置被设计用于横向电场（TE）偏振，并且同样地，横向磁（TM）偏振具有高得多的损耗。 </li><li>扫描的波长范围内的感兴趣的可调谐激光器（1510 nm至在这种情况下1600纳米），并监视的功率表。在透射光谱的任何伪像可能是由于从纤维片界面极化和标准具效应的TM分量的组合。 </li><li>定位在频谱中的谐振波长，并且还提取每个共振的带宽。这种特殊的芯片具有带宽小如65时，其转换为至多23000的品质因数（Q）。 </li><li>确定自由光谱范围（FSR），谐振器之间的距离，对于每个相邻的一对共振的。这种特定的设备具有〜5nm的FSR。 </li><li>计算使用下面的公式FSR的每个值的导模的群折射率（n g）项 : N 5&quot; SRC = "/文件/ ftp_upload / 55257 / 55257eq5.jpg"/&gt; 其中λ为波长，r是微环形谐振腔的半径。上面的等式是组索引的一个一阶近似。 </li><li>使用每个谐振的带宽，以确定与该组索引的每个值相关联的宽度性（Δn 克 ）。 </li><li>选择用于两个泵浦激光器，使得它们在光谱共振重合和具有奇数个（ 图1C）在它们之间谐振的波长。 </li><li>确定使用下面的等式的简并双光子的波长: <img alt="公式6" src="/files/ftp_upload/55257/55257eq6.jpg" /> 其中λ 泵1和λ 泵2是泵的光子的波长。 </li><li>添加水平线上组索引相对于波长，这两个泵浦波长（ 图3）之间延伸的曲线图。如果有可能的林e的n 克内的所有感兴趣的三个波长同时坐±Δ 体中 ，相位匹配条件得到满足，并且可以通过SFWM生成光子。如果它是不可能的，尽量选用泵浦波长更密切的一起，并再次检查。 </li></ol></li><li>第二可调谐激光源和偏振控制器添加到安装和从与1×2光纤合并两个激光器结合的光输出。 </li><li>立即芯片之前添加了一系列的基于光纤的陷波滤波器（其中足以达到衰减〜120分贝）。 注意:滤波器允许既泵浦波长通过，但拒绝该双光子波长。它们有助于耦合到所述芯片之前，以除去过量的噪声（ 即，宽带拉曼光纤散射）。该过滤器光谱示于图1B。 </li><li>添加一系列的基于光纤的带通滤波器（其中足以达到衰减〜150分贝）后立即芯片。 注:过滤器应足够宽，使双光子通过，但足够窄拒绝泵光子。需要两套这些，对于每个输出一组。该过滤器光谱示于图1B。 </li><li>从各组过滤器发送拒绝光子分离功率计。 注意:这些电表用于监控光耦合到芯片也可用于确定泵激光器的谐振剩余。 </li><li>从每个组的基于纤维的过滤器的单独的光输出连接到单光子检测器（SPD）和来自SPD的两个电信号输出连接到一个重合相关器。 </li><li>交叉的一对钨的探针，并设置提示向下螺旋的一条腿（〜长度为1毫米）的MZI。 </li><li>连接电源到两个交叉的探针，使得当施加电压时它们所产生的热量。这将作为移相器对于t他MZI。 注意:请参阅用于更标准化的方法的光子器件的热调谐的描述讨论。 </li></ol> 4.测量双光子干涉<ol><li>调两个泵浦激光器所选择的波长。使用被监控拒绝泵浦光子以确保两个激光器调谐到谐振电源米。当激光器被正确地调谐到所需的共振，从过滤器的拒绝信号将被最大化。 </li><li>来自每个激光器设置的光功率输出至-3 dBm的。 注意:这将导致&lt;100μW在芯片。它保持泵浦功率这种低，以便最小化损失（由多光子吸收和自由载流子吸收）和保持稳定性（通过最小化光诱导热偏移）是重要的。 PN结可以用来从波导除去运营商更好地适应更高的泵浦功率。 </li><li>监控巧合计数（同步跨过两个端口理性单打）通过〜220个PS上积分有关数据的峰值。当最小的100个巧合计数已收集足够的积分时间已经过去了。 注:积分窗口应足够宽，以占浪涌保护器的定时抖动。 </li><li>设置了移相器的初始电压（ 例如，0V）的电源。 </li><li>扫描整个波长范围的可调谐激光器的一个，并使用所收集的拒绝泵浦光子确认感兴趣的共振位置的电表。设置泵激光器到对应于所希望的共振的波长。 注意:每个移相器的电压变化作为热调谐可以导致在谐振波长小偏移的时间来完成这一步是很重要的。 </li><li>收集来自重合相关器所产生的数据（单光子计数以及重合计数）为先前选择的积分时间。在此，第90号的积分时间被选为具有32皮秒的定时精度。 </li><li>增加由5毫伏施加到移相器上的电压。 </li><li>直到数据已经被收集的电压的所需的范围，重复步骤4.4-4.6。 注:最大电压被限制在2.4V，由于该电压以上的探针的快速降解。 </li><li>整合为每个电源电压一致的峰在〜220 ps至确定巧合的总数（ 图4）。 </li><li>集成了320纳秒由符合峰值客场取得了意外的巧合。使用这个结果计算重合高峰记号的数量。 </li><li>适合从用下面的修饰的正弦函数的每个检测器的单打计数: <img alt="公式7" src="/files/ftp_upload/55257/55257eq7.jpg" /> 其中A，B，C，D，E，和F是拟合参数。这种配合是必要的，因为非线性relationsh电压和引起的热偏移（相对相位）之间的IP。 </li><li>自变量转换为相对相位对于所有三组数据（单曲来自每个检测器和重合计数计数）用下面的等式: <img alt="方程8" src="/files/ftp_upload/55257/55257eq8.jpg" /> 其中B，C，D，和E是从步骤4.11的拟合参数。这种转换是可能的，因为一个MZI 12的公知的正弦传递函数。 </li><li>适合用下面的正弦函数的重合数据（具有相对相位作为独立变量）: <img alt="公式9" src="/files/ftp_upload/55257/55257eq9.jpg" /> 其中A和B是拟合参数。 </li><li>计算与下面的公式每个干涉图案的可见性: <img alt="10式" src="/files/ftp_upload/55257/55257eq10.jpg" /> 其中ƒ（θ）max和ƒ（ <em&gt;θ）min与 ƒ（θ）的最大值和最小值，分别。 1可视性对应于一个完美的干涉图案。 </li></ol>

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有针对的集成光子领域，以便光子器件的复杂和可扩展的系统是可行的，克服多重挑战。这些措施包括，但不限于:紧制造公差，从环境的不稳定性隔离，以及各种形式的损失最小化。有在上述协议，有助于最小化光子器件的损耗的关键步骤。 之一在损失最小化的最重要的要求是紧密匹配的纤维和波导的光学模式。部分困难从大模场直径的SMF（MFD）（〜10微米）的茎。上的集?...

硅有出息作为光电子平台量子信息处理1，2，3，4，5。一个量子光子电路的重要组成部分是光子源。光子对源已经从硅开发了微环谐振器的通过第三阶非线性方法制备的形式中，自发四波混频（SFWM）6，7，8。这些源能够产生对不可区分的光子，这是理想的，涉及光子缠结9实验的。 需要注意的是环形谐振器源可与顺时针和逆时针传播两个操作是很重要的，并且两个不同的传播方向是基因反弹相互独立。这允许单个环用作两个源。当从两个方向光学泵浦，这些源生成以下纠缠态: <img alt="式（1）" src="/files/ftp_upload/55257/55257eq1.jpg" />哪里<img alt="公式2" src="/files/ftp_upload/55257/55257eq2.jpg" />和<img alt="公式3" src="/files/ftp_upload/55257/55257eq3.jpg" />是独立产生算符为clockwise-和逆时针传播的双光子，分别。这是被称为N00N状态（N = 2）10纠缠态的一个非常理想的形式。 通过芯片上的马赫 - 曾德尔干涉仪（MZI）传递这种状态导致的状态: <img alt="公式4" src="/files/ftp_upload/55257/55257eq4.jpg" />最大巧合，巧合的零之间的这种状态在振荡两次经典的干涉的在MZI的频率，有效地加倍干涉仪10的灵敏度。这里，我们提出用于测试这种集成光子源和MZI设备的过程。

<table><tbody><tr><td>3-Axis NanoMax Flexure Stage</td><td>Thorlabs</td><td>MAX312D</td><td>Precision 3-axis stages</td></tr><tr><td>Three-Hole Fiber Stripping Tool</td><td>Thorlabs</td><td>FTS4</td><td>buffer stripping tool</td></tr><tr><td>Three Channel Piezo Controller</td><td>Thorlabs</td><td>MDT693B</td><td>Piezo controllers for NanoMax stages</td></tr><tr><td>Fiber Polarization Controller</td><td>Thorlabs</td><td>FPC562</td><td>3-Paddle fiber-based polarization controller</td></tr><tr><td>Fiber Cleaver</td><td>Thorlabs</td><td>XL411</td><td>Fiber cleaver</td></tr><tr><td>Standard V-Groove Fiber Holder</td><td>Thorlabs</td><td>HFV001</td><td>standard v-groove mount</td></tr><tr><td>Tapered V-Groove Fiber Holder</td><td>Thorlabs</td><td>HFV002</td><td>tapered v-groove mount</td></tr><tr><td>Right-Angle Top Plate for NanoMax Stage</td><td>Thorlabs</td><td>AMA011</td><td>right-angle bracket</td></tr><tr><td>50:50 Fiber Optic Coupler</td><td>Thorlabs</td><td>TW1550R5F1</td><td>50/50 combiner</td></tr><tr><td>Optical Fiber Fusion Splicer</td><td>Fujikura</td><td>FSM-40S</td><td>Fusion splicer</td></tr><tr><td>MultiPrep Polishing System - 8&quot;</td><td>Allied High Tech</td><td>15-2100</td><td>Chip polisher</td></tr><tr><td>GreenLube</td><td>Allied High Tech</td><td>90-209010</td><td>Polishing Lubricant</td></tr><tr><td>Cross-Sectioning Paddle with Reference Edge</td><td>Allied High Tech</td><td>15-1010-RE</td><td>Polishing mount</td></tr><tr><td>Lightwave Measurement System</td><td>Keysight</td><td>8164B</td><td>Mainframe for tunable laser</td></tr><tr><td>Tunable Laser Source</td><td>Keysight</td><td>81606A</td><td>Tunable laser</td></tr><tr><td>Optical Power Sensor</td><td>Keysight</td><td>81634B</td><td>Power meter</td></tr><tr><td>NIR Single Photon Detector</td><td>ID Quantique</td><td>ID210</td><td>Single photon detectors</td></tr><tr><td>NIR Single Photon Detector</td><td>ID Quantique</td><td>ID230</td><td>Low noise, free-running single photon detectors</td></tr><tr><td>PicoHarp</td><td>PicoQuant</td><td>PicoHarp 300</td><td>Time-correlated single photon counting</td></tr><tr><td>WiDy SWIR InGaAs Camera</td><td>NIT</td><td>640U-S</td><td>IR Camera</td></tr><tr><td>WDM Bandpass Filter</td><td>JDS Uniphase</td><td>30055053-368-2.2</td><td>pump cleanup filters</td></tr><tr><td>WDM Bandpass Filter</td><td>JDS Uniphase</td><td>1011787-012</td><td>pump rejection filters</td></tr><tr><td>Ultra-High Numerical Aperture Fiber</td><td>Nufern</td><td>UHNA-7</td><td>high index fiber</td></tr><tr><td>Ultra Optical Single Mode Fiber</td><td>Corning</td><td>SMF-28</td><td>standard single mode fiber</td></tr></tbody></table>

measurement of quantum interference in a silicon ring resonator photon source

硅光子芯片必须实现复杂的集成量子信息处理电路，包括光子源，量子位操作和集成的单光子检测器的潜力。这里，我们提出准备和具有集成光子源和双光子干涉仪测试硅光子量子芯片的关键方面。使所有的产生的光子与最高可能的保真度检测的集成量子电路的最重要的方面是最小化损失。在这里，我们描述了如何通过使用超高数值孔径光纤到硅波导的模式紧密地匹配以进行低损耗边缘耦合。通过使用优化熔接配方中，娜纤维无缝地与标准单模光纤接口。这种低损耗耦合允许高保真光子产生的在集成硅环形谐振器的测量和产生的p的后续双光子干扰hotons在紧密结合Mach-Zehnder干涉。本文介绍的高性能和可扩展的硅量子光子电路的制备和表征的基本程序。

来自每个检测器，以及重合计数单个光子计数，当两个路径之间的相对相位进行了调整收集。各个计数（ 图5A）示出了从一个MZI具有94.5±1.6％和94.9±0.9％能见度经典干涉图案。的符合测量（ 图5B）显示了纠缠态的量子干涉，由振荡作为显然以两倍于传统干涉图案的频率，具有93.3±2.0％的可见性（96.0±2.1与临时记号％减去） 。为了证实主要被在环?...

Watch this Scientific Journal Video about Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source at JoVE.com

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

硅光子芯片必须认识到复杂的集成量子系统的潜力。这里介绍的是用于制备和测试对于量子测量硅光子芯片的方法。

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 ...

measurement-quantum-interference-silicon-ring-resonator-photon

Universidad San Sebastian

Research

JoVE Journal

Engineering

8.3K 次观看.  Rochester Institute of Technology. 硅光子芯片必须认识到复杂的集成量子系统的潜力。这里介绍的是用于制备和测试对于量子测量硅光子芯片的方法。 

视频: Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

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

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 ...

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 ...

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 ...

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 ...

Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization.

The fabrication process and experimental characterization techniques relevant to single-electron pumps based on silicon metal-oxide-semiconductor quantum dots are discussed.

硅金属 - 氧化物 - 半导体量子点单电子泵

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by ...

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 ...

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 ...

Generation and Coherent Control of Pulsed Quantum Frequency Combs

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

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

脉冲量子频率梳的产生与相干控制

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