Realization of One-Dimensional Dynamic Broadband Router

该项目旨在展示一种基于工程超材料的路由器，该路由器能够通过在红外光谱上施加外部偏置来连续调整反射角度。这种动态宽带光路由器，如果实现，将使光束的远场转向，使新的光学系统功能，如信号多路复用和路由。目前，与该系统最接近的解决方案是基于MEMS微镜和液晶空间光调制器的解决方案。与这些已知系统相比，所提出的设备在切换速度、紧凑性和通用可重构性方面具有革命性，并且没有移动部件。该计划开发的物理和设计原理、大面积制造技术和软件将证明对拟议的动态消色差光学路由器的未来发展是无价的。所有的共同研究者都将监督本科生，包括那些在科学和工程领域代表性不足的群体的学生，他们在这一重要领域有着广泛的记录。合作项目将采用统一的行动计划，将纳米光子学纳入课程，包括纳米光子学课程和可公开获取的课堂笔记。此外，合作pi将在各自的社区（例如科学博物馆和科学博览会）为K-12学生组织和建立夏季体验研讨会，该活动将与机构密切协调，并每年向美国国家科学基金会报告。他们还将组织暑期学校，重点是少数民族和代表性不足的参与者。设计超表面的传统方法依赖于亚波长、近共振、金属或介电散射体作为构建块。这种方法的主要缺点是，波前的整形只能针对一个频率进行设计，因为每个谐振器的散射相位以高度非线性的方式依赖于频率。实际上，实现在广泛的频率范围内无色差地工作的元表面仍然是一个艰巨的挑战。结合起来，这种异常反射的电可调性将代表一个真正革命性的设备概念，它可以潜在地以破坏性的方式应用于各种光学系统。在这里，合作伙伴提出了新的策略来做到这一点。实现这种调谐所需的异常反射是由ITO纳米间隙结构中间隙等离子体介导的亚波长尺度纳米结构超表面上的相位梯度引起的。电调谐是通过ITO材料实现的，它可以改变间隙等离子体的相速度，并表现出真正的时间延迟，从而允许电光控制。本项目将设计上述一维动态消色差光路由器，制作器件，评估其性能和基本极限，并进行散射测量来验证理论。该器件将通过一种独特的高通量纳米制造方法——原子层光刻技术实现，该方法使我们能够实现这项工作所需的超高纵横比金属沟槽。如果实现，所提出的设备构成了一个电控等离子体光路由器，可用于各种光学系统，特别是在逐像素的光路消色差控制是必不可少的，否则无法实现当前最先进的技术。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。

This program seeks to demonstrate an engineered metamaterial-based router capable of continuously tuning the angle of reflection via an externally applied bias across the infrared spectrum. Such a dynamic broadband optical router, if realized, would enable the far-field steering of beams, enabling new optical system functionalities such as signal multiplexing and routing. Today, the closest state-of-the-art solutions to the proposed system are ones based on MEMS micro-mirrors and liquid crystal spatial light modulators. In comparison to these known systems, the proposed device would be revolutionary in terms of switching speed, compactness, and versatile reconfigurability with the benefit of no moving parts. The physical and design principles, large-area manufacturing technologies, and software developed in this program will prove invaluable for future developments of the proposed dynamic achromatic optical router. All co-investigators will supervise undergraduate students, including individuals belonging to under-represented groups in sciences and engineering, building on their extensive track record in this important area. Co-PIs will employ a unified plan of action to incorporate nanophotonics into curricula, including classes in nanophotonics and openly accessible lecture notes. Furthermore, co-PIs will organize and establish a summer experience workshop for K-12 students in their respective community e.g. in Science Museums and Science Fair, an activity that will be closely coordinated with the institution and reported to NSF annually. They will also organize summer school, with emphasis on minority and under-represented participants. Conventional approaches to the design of metasurfaces rely on subwavelength, near-resonance, metallic or dielectric scatterers as building blocks. The major drawback of such an approach is that the shaping of the wavefront can only be engineered for a frequency, since the scattered phase for each resonator depends on frequency in a highly nonlinear fashion. Indeed, the implementation of metasurfaces that function achromatically across a broad range of frequencies remains a formidable challenge. In conjunction, the electrical tunability of such anomalous reflection would represent a truly revolutionary device concept which can potentially employed in a variety of optical systems in a disruptive manner. Here, co-PIs propose novel strategies to do just that. The anomalous reflections required to achieve this tuning are induced by a phase gradient along a sub-wavelength-scale nanostructured metasurface mediated by gap plasmons within ITO based nanogap structures. Electrical tuning is achieved through ITO materials, which modifies the phase velocity of the gap plasmons and exhibits true time delay which allows for electro-optic control. This program will design the above-mentioned one-dimensional dynamic achromatic optical router, fabricate the device, evaluate its performance and fundamental limits, and perform scatterometry measurement to corroborate with theory. The device will be realized with a unique high-throughput nanomanufacturing method, atomic layer lithography that allows us to realize ultrahigh-aspect-ratio metal trenches needed for this work. If realized, the proposed device constitutes an electrically controllable plasmonic optical router that can be employed in a variety of optical systems, specifically where achromatic control of the light path on a pixel-by-pixel basis is essential, and cannot otherwise be achieved with current state-of-the-art.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.