Collaborative Research: Three-Dimensional Laser Holographic Nanopatterning Using Metamaterial Phase Masks

人们迫切需要在太空和激光波长上可数字控制的纳米制造技术。这些新技术被期望产生空间变化的纳米结构，用于从电子学到光子学到能量存储的广泛应用。例如，梯度多重对称纳米结构可提高有机发光器件的光提取效率，光伏器件中的光耦合效率，以及光电探测器中的光吸收。该奖项研究纳米结构和工艺设计原则，涉及激光光束通过超材料光掩模和选择性激光材料去除，导致复杂功能纳米系统的形成。尽管在单一波长方面取得了进展，但还缺乏一种基于光掩模的纳米制造技术，可以高分辨率地引导多个波长的激光。该项目为未来并行、多波长、空间变化的三维纳米刻蚀铺平了道路，可以显著简化半导体行业使用的光刻工艺。该项目为本科生和研究生提供纳米制造、光学设计、模拟和表征领域的教育机会。它还包括通过沃斯堡科学和历史博物馆吸引妇女和未被充分代表的少数群体参与研究和针对普通公众的外联活动。该项目研究使用在多个激光波长下设计和操作的新型超材料相位掩模来制造新型空间梯度纳米结构的激光全息纳米制造。当前的相位掩模图案化技术顺序地控制光。例如，在传统的具有两层光栅的介电相位掩模中，由第一层光栅调制的光再次被第二层光栅调制。为了实现激光在空间和波长上的选择性调制，新的相位掩模概念由分布在一层或两层的谐振器组成，这些谐振器可以独立地、同时地、即并行地实现所需的多个波长的相位和幅度分布。利用基于等离子体谐振器的新型超材料相位掩模，激光只需通过设计预先确定的谐振器进行调制，就可以在空间梯度光子超晶体结构中制造出具有高空间分辨率和特征尺寸从微米到100 nm的三维纳米结构。总体而言，单等离子体元件和基于单次曝光的纳米制造工艺为实现空间梯度纳米结构提供了一种高效的方法，具有简单的光学设置，可用于许多应用。

There is a strong need for nanomanufacturing technologies that are digitally controllable in space and in laser wavelength. These new technologies are desired to generate spatially varying nanostructures for a wide range of applications from electronics to photonics to energy storage. Examples include gradient multiple-symmetry nanostructures to improve light extraction efficiency of organic light emitting devices, light coupling efficiency in photovoltaic devices, and light absorption in photo-detectors. This award investigates nanostructure and process design principles involving laser beam steering through a metamaterial photomask and selective laser material removal, leading to the formation of complex functional nanosystems. Despite progress at single wavelengths, a photomask-based nanofabrication technology that can steer lasers at multiple wavelengths at high resolution is lacking. This project paves the way for future parallel, multi-wavelength, spatially varying three-dimensional nanopatterning that can significantly simplify the photolithography process used by the semiconductor industry. The project provides education opportunities in the fields of nanomanufacturing, optical design, simulation and characterization to students at both undergraduate and graduate levels. It also includes outreach activities engaging women and under-represented minorities in research and targeting the general public via the Fort Worth Museum of Science and History.This project investigates laser holographic nanofabrication of a new type of spatially-gradient nanostructure using new metamaterial phase masks designed and operated at multiple laser wavelengths. The current phase mask patterning technology controls light sequentially. For example, in traditional dielectric phase masks with gratings in two layers, the light modulated by the first layer grating is modulated again by the second layer grating. In order to realize selective laser modulation in space and in wavelength, the new phase mask concept consists of resonators distributed in one or two layers that can be used to realize desired phase and amplitude profiles at multiple wavelengths independently and simultaneously, namely, in parallel. Using the new plasmonic resonator-based metamaterial phase mask, the laser light is only modulated by resonators pre-determined by design, leading to the manufacturing of 3D nano-architectures with high spatial resolution and feature size reduction from microns to 100 nm in spatially-gradient photonic super-crystal structures. Overall, the single plasmonic element and single exposure-based nanofabrication process provides a highly efficient approach with a simple optical setup for realizing spatially-gradient nanostructures for many applications.