NER: Femtosecond-Laser-Induced Self-Assembly of Nanograting on Nanowires: An Enabling Technique for Nanowire-Based Active Nanophotonics

本研究的目的是直接在独立纳米线（NWs）上绘制一维（1D）周期纳米结构，展示光栅周期的基本控制，并研究其作为线上光栅的适用性。这项技术是基于我们最近发现的激光驱动自组装工艺：在含有六羰基钨的大气中，将近紫外飞秒激光束轻轻聚焦到衬底上，几乎在任何材料上都能自发形成钨纳米结构的一维阵列。通过对衬底进行激光扫描，可以得到具有良好长程有序度的钨纳米光栅。这项研究的智力优势在于，我们的技术可能是一种单步、单光束、室温和干燥的工艺，可以直接在独立的NWs上绘制光栅图样。线上纳米光栅有望成为纳米光子学的基本组成部分。然而，在传统光刻技术中，纳米粒子由于尺寸小，对化学污染越来越敏感。另一方面，我们的方法只涉及一步，因此可以保持它们的化学和物理完整性。更广泛的影响：TNG作为线上光栅可以在基于nw的有源纳米光子学中实现许多新的应用，例如激光，化学和机械传感器。参与该项目的研究生和本科生将有机会开展飞秒激光纳米制造的前沿研究。此外，我们将为高中生提供暑期研究机会，让他们在我们实验室的研究生指导下参与这个项目，让他们接触到纳米科学和技术的新兴领域。

The objectives of this research are to pattern one-dimensional (1D) periodic nanostructures directly on free-standing nanowires (NWs), demonstrate rudimentary control of the grating periods, and investigate their suitability as on-wire optical grating. This technique is based on our recently discovered laser-driven self-assembly process: by gently focusing a near-UV femtosecond laser beam onto substrates in an atmosphere containing tungsten hexacarbonyl, 1D array of tungsten nanostructure forms spontaneously on almost any materials. Tungsten nanograting (TNG) with excellent long-range order can be obtained by scanning the substrates across the laser beam.The Intellectual Merits of this research lie in the fact that our technique is potentially a single-step, single-beam, room-temperature, and dry process to pattern gratings directly on free-standing NWs. On-wire nanograting is expected to become a fundamental building block for NW-based nanophotonics. However, NWs are increasingly sensitive to the chemical contamination in conventional lithography due to their small dimensions. Our method, on the other hand, involves only single step and therefore could preserve their chemical and physical integrity. Broader Impacts: TNG as on-wire optical grating could enable a host of new applications in NW-based active nanophotonics such as lasers, chemical and mechanical sensors. Graduate and undergraduate students involved in this project will have opportunity to carry out cutting-edge research in femtosecond laser nanofabrication. Besides, we will offer high-school students summer research opportunity to participate in this project under supervision of graduate students in our laboratory and to expose them to the emerging field of nanoscience and technology.