EAGER: Enhanced Optical Pressure from Nanostructured Metal Films

来自纳米结构金属膜的光学压力增强普渡大学的Kevin Webb和徐先帆提出了一项关于纳米结构材料中光学力的理论和实验相结合的研究，旨在建立一种控制小颗粒上的纳米尺度力并增强结构表面上的总压力的方法。因此，对小颗粒的大作用力和对膜的总作用力是可以预期的。虽然光学镊子现在已经可以商业化，但它们对于移动附着着生物分子的大珠子是有效的。像量子点一样定位纳米粒子需要很大的局部作用力，这可以通过控制金属表面的几何形状来实现。这将避免光钳中对大珠子的需要，并为通过纳米级光学组装合成新材料提供了一种途径。此外，光提供的相对较弱的压力的大幅增加将允许在机械控制中使用较弱的光信号。由此产生的光学机械系统可以比光电子系统更简单、更通用，从而打开了通信和传感的机会。具体地说，虽然已经认识到全光网络可以提高速度和效率，但对于如何提供这种方法可以解决的网络重新配置仍然存在挑战。在基本层面上，这项工作将提供纳米尺度的实验力数据，用于建立可用于设备设计的模型。该项目的目标是设计和制造具有共振纳米级狭缝的金膜，有望在整体压力下产生显著的增强。这种增加力的方法的验证将允许使用这种方法在各种自由空间和波导布置中使用激光来机械控制表面。该项目将为纳米光子结构的设计奠定基础，这种结构可以提供大量且可控的光学力，以驱动光子网络中的调谐元件。这将简化交换技术，该方法有可能降低能耗和成本。该项目将促进传感，允许分子移动到具有大场从而大拉曼偶极矩的区域以进行识别。这种纳米级的陷阱可以用于材料合成，例如，允许将量子点捕获在纳米空间中，以实现光源和探测器。虽然光学镊子变得越来越常见，但绝对力的确定依赖于宏观校准程序，这些程序无法获得纳米级的力。通过评估材料、几何和力之间的关系，应该可以设计出具有更大力的镊子，以在局部移动较小的对象或较大的对象。通过控制光学材料的电和磁性能，也应该有新的机会。在根本层面上，这项拟议的工作可能会为长达一个世纪的关于光学力描述的辩论提供一个答案。

Enhanced Optical Pressure from Nanostructured Metal FilmsKevin Webb and Xianfan Xu, Purdue UniversityA combined theoretical and experimental study of optical forces in nanostructured material is proposed to establish a method to control the nanometer-scale force on a small particle and to provide enhancement in the total pressure on a structured surface. Consequently, large forces on small particles and an increase in the total force on a membrane are expected. While optical tweezers are now commercially available, they are effective for moving large beads to which, for example, biological molecules are attached. Positioning nanoparticles like quantum dots requires large and local forces that can be achieved with control over the geometry of a metal surface. This would circumvent the need for the large beads in optical tweezers and provide an approach for synthesizing new materials by nano-scale optical assembly. Furthermore, the substantial increase in the relatively weak pressure provided by light will allow weaker optical signals to be used in mechanical control. The resulting optomechanical system can be simpler and more versatile than optoelectronic systems, opening communication and sensing opportunities. Specifically, while it has been recognized that all-optical networks can increase both speed and efficiency, there remain challenges as to how to provide network reconfiguration that this approach could address. At the fundamental level, this work will provide experimental force data on the nanometer scale that will be used in establishing a model that can be used for device design. The goal of this project is to design and fabricate gold films with resonant nanometer-scale slots that are expected to produce a dramatic enhancement in the overall pressure. The verification of this method for increasing the force will allow the approach to be used to mechanically control a surface using laser light in various free space and waveguide arrangements. The project will lay the design foundations for nanophotonic structures that impart substantial and controllable optical forces to actuate tuning elements in photonic networks. This will simplify switching technology and the approach has the potential to reduce energy consumption and cost. This project will facilitate sensing, allowing a molecule to be moved to a region with large field and hence large Raman dipole moment for identification. Such nanoscale traps could be used in material synthesis, allowing trapping of quantum dots in nanocavities for achieving optical sources and detectors, for instance. While optical tweezers are becoming more common, determination of the absolute force relies on macroscopic calibration procedures that do not provide access to the force on the nanometer scale. By evaluating the relationship between materials and geometry and the force, it should be possible to design tweezers with larger forces to move smaller objects or larger objects locally. There should also be new opportunities through control of the optical material properties, both electric and magnetic. At the fundamental level, the proposed work may provide an answer to a century-long debate about the description of the optical force.