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，其中其属性可以改变以实现不同的物理和光学行为，对于从光谱学到成像的各种应用具有广泛的兴趣。这些组件中的大多数为了可调谐而牺牲了光学性能，并且它们是使用难以小型化的结构和工艺制造的。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化物材料和纳米结构，这些材料和纳米结构具有可逆的非晶到晶体相变，以具有定制的折射率值和连续可调的色散特性。这种硫系相变材料的问世将利用与相变相关的极大的折射率变化来开发新的紧凑、可调的光学元件。该项目中正在开发的硫化物材料和工艺可通过美国国家科学基金会资助的国家纳米技术基础设施网络广泛获得。技术描述：具有成分定制、光谱可调和可逆特性的光学材料在生产具有独特功能的光学元件方面具有吸引力。硫系相变材料(PCM)在脉冲热、光或电刺激下表现出快速、可逆的非晶态到晶态相变。然而，目前基于硫系相变材料的光学器件只利用了与材料的纯非晶态和纯晶态之间的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，以确定一种硫化物组合物，该组合物能够控制空间分散的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分散度方面产生连续可调和可重复的变化。对于每一种成分，正在对块体、薄膜和纳米薄膜进行表征，以了解与器件相关的边界条件在外部光或热激发诱导的成核和生长过程中的作用。应用补充技术来了解材料的本征响应和定制的光学性能之间的基本关系，包括热、结构和光学测量和分析。在本项目期间收集的结构-性质数据将提供使用硫族化合物相变材料设计完全可调光学元件所需的关键输入。一个新的指导团队项目，将大学和行业合作的研究人员联系起来，培训研究生和本科生拥有与全球相关的劳动力技能。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)，该项目正在开发的硫化物相变材料和工艺可供更广泛的外部学术界和工业界使用。

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.