Collaborative Research/GOALI: Engineered Crystallization Behavior of Phase Change Materials to Enable Advanced Optical Functionalities

非技术描述：可调谐光学元件，其性质可以改变以实现不同的物理和光学行为，广泛应用于从光谱学到成像的各种应用。大多数这些组件牺牲光学性能的可调性，他们制造的结构和工艺很难小型化。在这个合作项目中，来自中佛罗里达大学、宾夕法尼亚州立大学和洛克希德·马丁公司的研究人员正在优化红外硫族化物材料和纳米结构，这些材料和纳米结构表现出可逆的非晶到晶体的相变，从而具有可连续调谐的量身定制的折射率值和色散特性。这种硫系相变材料的可用性将通过利用与相变相关的异常大的折射率变化来开发新的紧凑、可调谐的光学元件。在这个项目中开发的硫系化合物材料和工艺可以通过nsf资助的国家纳米技术基础设施网络广泛地获得。技术描述：具有光谱可调和可逆特性的光学材料对于生产具有独特功能的光学元件具有吸引力。硫系相变材料（PCMs）在脉冲热、光或电刺激下表现出快速可逆的非晶相变。然而，目前基于硫系pcm的光学器件仅利用了与材料的纯非晶态和纯晶态之间转变相关的光学反射率的巨大变化。在这个合作项目中，来自中佛罗里达大学、宾夕法尼亚州立大学和洛克希德·马丁公司的研究人员正在进行实验研究，以确定一种硫族化合物成分，这种成分可以控制空间分散纳米晶体的成核和生长，这将在复合玻璃陶瓷材料的红外折射率和色散方面产生连续可调和可重复的变化。对于每种组合物，体、薄膜和纳米化薄膜都进行了表征，以了解与器件相关的边界条件在由外部光学或热激发诱导的成核和生长过程中的作用。互补技术正在被应用于理解材料固有响应和定制光学性能之间的基本关系，包括热、结构和光学测量和分析。在该项目中收集的结构属性数据将为设计使用硫系pcm的完全可调谐光学元件提供关键输入。一项新的指导团队计划将大学和行业合作研究人员联系起来，培训研究生和本科生掌握与全球相关的劳动力技能。在这个项目中开发的硫系相变材料和工艺可以通过位于宾夕法尼亚州立大学的nsf资助的国家纳米技术基础设施网络（NNIN）向更广泛的外部学术界和工业界提供。

NON-TECHNICAL DESCRIPTION: Tunable optical components, ones where their properties can be altered to realize different physical and optical behavior, are of widespread interest for diverse applications ranging from spectroscopy to imaging. Most of these components sacrifice optical performance for tunability and they are manufactured using structures and processes that are difficult to miniaturize. In this collaborative project, researchers from the University of Central Florida, Pennsylvania State University, and Lockheed Martin are optimizing infrared chalcogenide materials and nanostructures that exhibit reversible amorphous-to-crystalline phase transitions to have tailored refractive index values and dispersive properties that are continuously tunable. The availability of such chalcogenide phase change materials will enable the development of new compact, tunable optical components by exploiting the exceptionally large refractive index change associated with the phase transition. The chalcogenide materials and processes being developed in this project are broadly available through the NSF-funded National Nanotechnology Infrastructure Network.TECHNICAL DESCRIPTION: Optical materials with compositionally tailored properties that are spectrally tunable and reversible are attractive for producing optical components with unique functionalities. Chalcogenide phase change materials (PCMs) exhibit rapid and reversible amorphous-to-crystalline phase transitions in response to pulsed thermal, optical, or electrical stimuli. However, current optical devices based on chalcogenide PCMs have only exploited the large change in optical reflectance associated with the transition between the pure amorphous and the pure crystalline states of the material. In this collaborative project, researchers from the University of Central Florida, Pennsylvania State University, and Lockheed Martin are conducting experimental studies to identify a chalcogenide composition that enables controlled nucleation and growth of spatially dispersed nanocrystals, which will produce a continuously tunable and reproducible change in the infrared refractive index and dispersion of the composite glass ceramic material. For each composition, bulk, thin film, and nanopatterned films are being characterized to understand the role of device-relevant boundary conditions on the nucleation and growth process induced by external optical or thermal excitation. Complementary techniques are being applied to understand the fundamental relationship between the intrinsic material response and the tailored optical performance, including thermal, structural, and optical measurement and analysis. The structure-property data being collected during this project will provide the critical input needed to design fully tunable optical components using chalcogenide PCMs. A new mentoring team program, which links university and industry partnered researchers, trains graduate and undergraduate students to have globally-relevant workforce skills. The chalcogenide phase change materials and processes being developed in this project are available to the broader external academic and industrial community through the NSF-funded National Nanotechnology Infrastructure Network (NNIN) located at Pennsylvania State University.