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

本研究的目标是将一维(1D)周期性纳米结构直接在自支撑纳米线(NWS)上形成图案，展示对栅周期的基本控制，并研究其作为在线光纤光栅的适用性。这项技术是基于我们最近发现的激光驱动的自组装过程：通过在含有六酮基钨的大气中将近紫外飞秒激光束轻轻聚焦到衬底上，几乎在任何材料上自发形成一维钨纳米结构阵列。通过激光扫描衬底，可以获得具有良好长程有序的钨纳米级(TNG)。这项研究的智能优点在于，我们的技术潜在地是一步法、单光束、室温和干法直接在独立的纳米WW上形成栅图。线上纳米刻度有望成为基于NW的纳米光子学的基本构件。然而，由于原子核的尺寸较小，使得其对常规光刻中的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作为线上光纤光栅可以在基于NW的有源纳米光子学中实现一系列新的应用，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，在我们实验室的研究生指导下参与这个项目，并让他们接触到新兴的纳米科学和技术领域。

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.