High Throughput Tip-Enhanced Near Field Microscopy using Radially Polarized Fiber Modes

非技术描述：光学显微镜可以说是有史以来对显微世界进行非侵入性检查最成功的技术之一。在过去的十年里，纳米科学在长度尺度上比微尺度小几个数量级的现象，在广泛技术的发展中发挥了越来越大的作用，如纳米级半导体设备，医学中基于纳米颗粒的疗法，以及可以测量来自生物和无生命物理系统的微小作用力和信号的传感器。同样，纳米技术也加深了我们对纳米尺度基本科学现象的理解，例如有望带来下一代高速可穿戴电子设备的二维材料的电子结构，能够进行亚细胞分类的固有振动模式的图像，以及生物物理系统中重要蛋白质的局部存在。因此，纳米级的探测，特别是光学探测，对于帮助引领下一次科学技术革命至关重要，就像光学显微镜在微观世界中所做的那样。我们建议的光纤涡旋光源将在能够光学解决纳米级现象的设备中提供两到三个数量级的信号增强和背景降低。技术描述：该计划的目标是开发一种尖端增强型近场显微镜系统，该系统保留了当前散射型近场扫描光学显微镜的所有优势，包括使用成熟的弹性或非弹性散射技术探测纳米级材料的幅度和相位响应的能力，但吞吐量增加了几个数量级(模拟表明效率可能达到75%，而不是目前的实施方案的0.1-0.2%)。这将减少限制当前尖端增强显微镜系统应用的背景问题。实现计划目标的主要智力意义将是实现纳米级显微镜系统，该系统可以探测比目前可能的信号弱几个数量级的信号，这得益于基于光纤的纳米级尖端将实现的背景大幅减少。在拟议的工作中，我们将使用光纤锥化、电化学刻蚀技术和精密金属沉积技术，将光纤中稳定的径向偏振光学模式绝热转换为光纤尖端的等离子体模式，这是尖端增强显微镜所需的。绝热模式转换，而不是目前使用的外部照明，将是当前TIP增强显微镜系统和所提议的设备之间的关键区别，因为这有望在信号吞吐量方面产生两到三个数量级的增加和相应的本底减少。

Title: Tip-enhanced near-field microscopy using optical fiber vorticesNon-technical description: Optical microscopy is arguably one of the most successful techniques for non-invasive examination of the microscopic world ever created. In the last decade nanoscience, phenomena at length scales orders of magnitude smaller than the microscale, has played an increasingly larger role in the development of widespread technology such as nanoscale semiconductor devices, nanoparticle based therapies in medicine, and sensors that can measure minute forces and signals from biological as well as inanimate physical systems. Likewise, nanotechnology has also furthered our understanding of fundamental scientific phenomena at the nanoscale, such as the electronic structure of two-dimensional materials that promise to usher in the next generation of high-speed wearable electronic devices, images of intrinsic vibrational modes capable of sub-cellular classification and local presence of important proteins in biophysical systems. Probing, and in particular, optical probing at the nanoscale is thus of paramount importance to help lead the next revolution in science and technology much like the optical microscope did in the microscopic world. Our proposed optical fiber vortex light source will provide two to three orders of magnitude signal enhancement and background reduction in devices that can optically resolve nanoscale phenomena.Technical description: The goal of this proposed program is to develop a tip-enhanced near-field microscopy system that retains all the advantages of current scattering type near-field scanning optical microscopes, including the ability to probe the amplitude and phase response of materials in the nanometer scale using well-established elastic or inelastic scattering techniques, but with an increased throughput by several orders of magnitude (simulations suggest the possibility of 75% efficiencies, as opposed to 0.1-0.2% in current implementations). This will reduce background problems that have limited the application of current implementations of tip-enhanced microscopy systems. The primary intellectual significance of achieving program goals will be the realization of a nanoscale microscopy system that can probe signals orders of magnitude weaker than currently possible, aided by the dramatic reductions in background that an optical fiber-based nanoscale tip would enable. In the proposed effort we will use fiber tapering, electrochemical etching techniques, and precision metal deposition techniques to adiabatically convert the stable radially polarized optical modes in the fiber into plasmonic modes at the fiber tip, as required for tip-enhanced microscopy. The adiabatic mode transformation, as opposed to external illumination as is currently employed, will be the key differentiator between current tip-enhanced microscopy systems and the proposed device, as this is expected to yield the two-to-three orders of magnitude increase in signal throughput and corresponding decrease in background.