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

对空间和激光波长数字可控的纳米制造技术有着强烈的需求。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，用于提高有机发光器件的光提取效率、光伏器件的光耦合效率和光电探测器的光吸收的梯度多对称纳米结构。该奖项研究纳米结构和工艺设计原则，包括激光束通过超材料光掩膜和选择性激光材料去除，导致复杂功能纳米系统的形成。尽管在单波长方面取得了进展，但目前还缺乏一种基于光掩模的纳米制造技术，这种技术可以在高分辨率下操纵多波长的激光。该项目为未来平行、多波长、空间变化的三维纳米图案铺平了道路，可以大大简化半导体工业使用的光刻工艺。该项目为本科生和研究生提供纳米制造、光学设计、仿真和表征等领域的教育机会。它还包括通过沃斯堡科学与历史博物馆开展外联活动，让妇女和代表性不足的少数民族参与研究，并以公众为目标。本项目研究了一种新型空间梯度纳米结构的激光全息纳米加工，该纳米结构采用设计和操作在多个激光波长下的新型超材料相掩模。当前的相位掩模模式技术是按顺序控制光。例如，在传统的两层光栅介质相位掩模中，由第一层光栅调制的光被第二层光栅再次调制。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）实现多个波长上所需的相位和幅度分布。利用新的基于等离子体谐振器的超材料相位掩模，激光仅由设计预先确定的谐振器调制，从而制造出具有高空间分辨率的3D纳米结构，并且在空间梯度光子超晶体结构中特征尺寸从微米减小到100 nm。总的来说，单等离子体元件和基于单曝光的纳米加工工艺为实现空间梯度纳米结构提供了一种高效的方法，并具有简单的光学设置。

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.