Fabrication of High Performance Metasurfaces by Nanoimprinting of Refractive Index

该补助金支持制造研究，推进与光学设备制造有关的知识，这一努力促进了新兴技术的科学进步，有可能促进国家健康，繁荣和国防。 具体来说，这项研究推进了具有成本效益的纳米制造组件的关键能力，这些组件被称为超表面，可以通过几乎任意的波前成形控制来操纵光。 这一重要技术在生物医学成像、光通信、激光成像探测和测距以及激光捕获和太阳能应用的光学管理等领域具有相关性。 几乎所有目前可用的用于生产超颖表面的制造工艺都依赖于通过图案化随后进行材料蚀刻或沉积来结构化光学材料。这种通用方法面临着影响元表面性能、制造良率和可扩展性的基本限制。该项目进行基础研究，研究一种创新的制造途径，其中材料的光学特性被直接操纵并以高分辨率进行图案化，而无需任何沉积或蚀刻。除了支持现有超颖表面架构的制造之外，该方法还独特地实现了提供上级操作带宽和制造公差的新超颖表面设计。该奖项支持技术工人进入科学，技术，工程和数学职业的培训，为本科阶段的研究经验提供支持，提供将研究融入本科课堂的机会，鼓励妇女和代表性不足的少数民族，并支持当地的外展活动，培养K-12学生对科学的兴趣。这项工作的技术范围包括：（a）开发一种用于以纳米级分辨率在芯片表面上图案化折射率的方法，（B）将多孔纳米材料的形态学调节映射到有效的光学性质，（c）展示具有二元和任意折射率分布的高性能超颖表面的直接制造，以及（d）提供了一种用于非谐振（宽带）相位控制的变革性新方法，其克服了粒子间间距限制并提高了制造公差。本研究的重点是一种技术，其中多孔基板的局部压印和致密化，在高分辨率直接压印三维掌握邮票，然后平面化。为了开发这种纳米制造方法，以实现高性能超颖表面的成本效益的制造，这项研究解决了有关工艺参数，工艺变化和控制，机械完整性，光学质量和工艺限制的关键问题。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

This grant supports manufacturing research that advances knowledge pertaining to the fabrication of optical devices, an effort which promotes scientific progress in emerging technologies with the potential to advance national health, prosperity, and defense. Specifically, this research advances key capabilities in cost-effective nanomanufacturing of components known as metasurfaces, which can be tailored to manipulate light with almost arbitrary wavefront shaping control. This important technology holds relevance in areas such as biomedical imaging, optical communications, laser imaging detection and ranging, and optical management for laser trapping and solar energy applications. Nearly all currently available manufacturing processes for producing metasurfaces rely on structuring optical materials through patterning followed by material etching or deposition. This general approach faces fundamental limitations which impact metasurface performance, manufacturing yield, and scalability. This project conducts fundamental research that investigates an innovative fabrication pathway wherein a material's optical properties are directly manipulated and patterned at high resolution without any deposition or etching. In addition to supporting the fabrication of existing metasurface architectures this approach uniquely enables new metasurface designs offering superior operating bandwidths and fabrication tolerances. This award supports training of skilled workers to enter into science, technology, engineering, and math careers, provides support for research experiences at the undergraduate level, offers opportunities to integrate research within the undergraduate classroom, encourages women and underrepresented minorities and supports local outreach activities which fosters interest in science for K-12 students.The technical scope of this work includes: (a) developing a method for patterning refractive index on the surface of a chip with nanoscale resolution, (b) mapping the morphological tuning of porous nanomaterials to effective optical properties, (c) demonstrating the straight-forward fabrication of high performance metasurfaces with both binary and arbitrary refractive index profiles, and (d) offering a transformative new approach for non-resonant (broadband) phase control which overcomes interparticle spacing limitations and improves fabrication tolerance. This research focuses on a technique wherein porous substrates are locally imprinted and densified at high resolution by direct imprinting with three-dimensionally mastered stamps then planarized. With the aim of developing this nanomanufacturing approach to enable the cost effective fabrication of high performance metasurfaces, this research addresses key questions regarding process parameters, process variation and control, mechanical integrity, optical quality, and process limitations.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.