Optically resonant nanotweezers using dielectric bowtie cavities

许多日常的简单任务都涉及移动物体，比如我们的手机和咖啡杯，从一个位置移动到另一个位置。然而，当对象变得太小而不方便用手拿着时，就需要新的方法来处理这样的小对象。操纵微观物体的一种优雅的方法是使用聚焦光束。这种被称为“光镊子”的技术获得了2018年诺贝尔物理学奖，并被广泛用于操纵细胞，以提高对生物系统的理解。然而，由于固有的无法将光聚焦到纳米级（十亿分之一米）的体积，用传统的光镊捕获纳米级物体的尝试遇到了重大挑战。为了应对这些挑战，并实现探测纳米世界的新能力，包括构成人类基因组基础的核酸和支持显示器和太阳能电池技术进步的量子点，pi将开发光学纳米结构，使用硅将光压缩到非常微小的纳米级体积。pi提出的方法可以捕获直径至少比人类头发厚度小一万倍的极小的纳米级物体。这种工具将为科学家提供探索纳米世界的新工具，并有可能在从传感到量子计算等应用领域实现新的科学发现。教师和研究生将开发活动，以促进STEM（科学，技术，工程和数学）在田纳西州中部的初高中学生。捕获和动态操纵纳米尺度物体的能力对纳米技术的进步至关重要。光学捕获被广泛用于微尺度物体的稳定捕获。然而，由于无法使用自由空间光学将光聚焦到纳米尺度的物体上，试图将它们转化为纳米尺度的物体遇到了挑战。近十年来，基于等离子体纳米天线的近场纳米光镊已经得到了发展，但损耗引起的热效应对处理脆弱的生物物体提出了一个主要挑战。本研究的目的是证明在二维介电领结光子晶体腔（PhCs）中利用极受限电磁场捕获、快速传输和稳定捕获亚毫瓦光功率的亚20nm介电物体和量子发射体是可能的。为了实现这些目标，将设计和制造具有超低模体积和窄共振线宽的二维硅领结PhCs。所提出的活动的智力意义包括：(a)理解由于粒子在高质量因子领结腔中的位置而引起的自诱导反作用力对光捕获性能的作用；(b)解决纳米尺度物体向领结腔高能量密度区域的低捕获率和扩散限制的传输问题；(c)了解热泳力对捕集性能的作用；(d)实现纳米物体在光学腔间的远距离输运，这是目前尚未实现的。该项目将使学生接触不同领域的研究，包括纳米光学、纳米制造、材料表征、微流体和先进的多物理场建模。项目成员将通过参与范德比尔特大学已经建立的成功项目，参与针对初高中学生的科学和技术推广活动。通过这些拓展和教育活动，研究人员希望激发年轻一代的兴趣，鼓励他们追求以stem为重点的职业。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Many everyday simple tasks involve moving objects, such as our cell phones and coffee mugs, from one position to another. However, when the objects become too small to be conveniently held by hand, new approaches are needed to handle such small objects. An elegant approach to manipulate microscopic objects is to use a focused light beam. Known as "optical tweezers", this technique was recognized with the 2018 Nobel prize in Physics and is widely used to manipulate cells to enable improved understanding of biological systems. However, because of the inherent inability to focus light to nanoscale (one-billionth of a meter) volumes, attempts to trap nanoscale objects with conventional optical tweezers have met significant challenges. To address these challenges and enable new capabilities for probing the nano-world, including nucleic acids that form the basis of our human genome and quantum dots that support technological advances in displays and solar cells, the PIs will develop optical nanostructures using silicon to squeeze light to very tiny, nanoscale volumes. The approach proposed by the PIs could enable the trapping of extremely small nanoscale objects with diameters that are at least ten thousand times smaller than the thickness of the human hair. Such a tool will equip scientists with new tools to probe the nano-world and potentially enable new scientific discoveries in application areas ranging from sensing to quantum computing. Faculty and graduate students will develop activities to promote STEM (science, technology, engineering, and mathematics) with middle and high school students in middle Tennessee.The ability to trap and dynamically manipulate nanometer-scale objects is crucial to the advancement of nanotechnology. Optical trapping is widely used for stable trapping of microscale objects. However, attempts to translate them for use to handle nanometer scale objects have been met with challenges because of the inability to focus light to nanoscale volumes using free-space optics. While near-field nano-optical tweezers based on plasmonic nanoantennas have been developed within the last decade, the loss-induced heating effect presents a major challenge for handling delicate biological objects. The objective of this research is to demonstrate that it is possible to capture, rapidly transport, and stably trap sub-20 nm dielectric objects and quantum emitters with sub-milliwatt optical power using the extremely confined electromagnetic field in 2D dielectric bowtie photonic crystal cavities (PhCs). To achieve these objectives, 2D silicon bowtie PhCs with ultra-low mode volume and narrow resonance linewidth will be designed and fabricated. The intellectual significance of the proposed activities includes: (a) an understanding of the role of self-induced back-action force due to the position of the particle in the high-quality factor bowtie cavities on the optical trapping performance; (b) addressing the issue of low capture rate and diffusion-limited transport of nanometer scale objects towards the region of high energy density in the bowtie cavity; (c) an understanding of the role of thermophoretic force on the trapping performance; (d) the realization of long-range transport of nanometric objects between optical cavities, which has remained elusive. The project will expose students to different fields of research including nano-optics, nanofabrication, materials characterization, microfluidics and advanced Multiphysics modeling. Project members will engage in science and technology outreach targeting middle and high school students by participating in successful programs already well-established at Vanderbilt. Through these outreach and educational activities, the researchers expect to spark the interest of the younger generation and encourage them to pursue STEM-focused careers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.