Collaborative Research: Thin-Film Chalcogenide Glass Materials for High-Quality Integrated Photonics

非技术描述：麻省理工学院和华盛顿大学合作研究项目的主要目标是：（1）通过光谱研究，对薄膜硫系玻璃材料的光学损耗机制进行深入了解;（2）利用创新的加工科学，合成薄膜形式的超低损耗硫系玻璃材料;（3）制造具有新功能的光学器件。基于这些基本发现，该研究旨在展示具有高品质因数的硫系玻璃谐振腔器件，作为光子传感器，光发射器和非线性光学信号处理系统的构建模块。该研究预计将对材料科学、纳米技术、非线性光学和集成光子学等许多领域产生重大影响。参与的本科生和研究生研究人员受益于麻省理工学院和华盛顿大学两个研究小组之间的跨学科合作。从研究中获得的结果被纳入新的本科课程玻璃材料在麻省理工学院。该项目还通过实验室开放日和暑期实习计划在两个校区扩展K-12计划。技术描述：硫系玻璃（ChG）被认为是集成光子学的新兴材料平台，因为它们具有独特的性质，例如衬底盲集成能力、极端的加工通用性、通过成分合金化可广泛调谐的光学和热特性、大的克尔非线性，和宽带光学透明度。与二氧化硅玻璃不同，多组分硫族化物玻璃包含更多样化的纳米级玻璃网络部分。这些性质导致复杂的结构转换和光学损失，是高度敏感的处理历史，不能使用经典的瑞利散射形式主义。因此，传统的损耗降低方法不能简单地转移到硫属化物材料，而不深入了解硫属化物膜中的微观结构演变和损耗机制的动力学。区分硫属化物薄膜中的光学损耗贡献的挑战进一步由薄膜中的小相互作用体积而复杂化，这严重限制了大多数传统光学表征方法的灵敏度。在该项目中，开发了新的基于波导和谐振器的光谱表征方法，以提取关键材料信息，如纳米级相组成，固有吸收和不同的散射过程。该项目推进了我们对与材料光学特性相关的纳米结构转变机制以及ChG材料中结构-加工-性质关系的理解。通过结合动力学建模和新型表面张力辅助加工技术的实验验证，该项目还旨在开发性能超过当前最先进水平的超高质量平面ChG结构。

Nontechnical Description: The main objectives of this collaborative research project between MIT and Washington University are (1) to develop critical understandings of the optical loss mechanisms in thin-film chalcogenide glass materials through spectroscopic studies, (2) to exploit innovative processing science to synthesize ultra-low-loss chalcogenide glass materials in the thin-film form and (3) to fabricate optical devices with novel functionalities. Based on these fundamental findings, the research aims to demonstrate chalcogenide glass resonant cavity devices with high quality factors as building blocks for photonic sensors, light emitters and nonlinear optical signal processing systems. The research is expected to have significant impacts on many areas including materials science, nanotechnology, nonlinear optics and integrated photonics. The participating undergraduate and graduate researchers benefit from the cross-disciplinary collaboration between the two research groups at MIT and Washington University. Results obtained from the research are incorporated into new undergraduate courses on glass materials at MIT. The project also expands K-12 initiatives on both campuses through lab open houses and summer internship programs.Technical Description: Chalcogenide glasses (ChGs) are recognized as an emerging material platform for integrated photonics given their unique properties, such as substrate-blind integration capacity, extreme processing versatility, widely tunable optical and thermal characteristics via composition alloying, large Kerr nonlinearity, and broadband optical transparency. Unlike silica glass, multi-component chalcogenide glasses contain a far more diverse group of nanoscale glass network moieties. These properties result in complicated structural transformations and optical losses that are highly sensitive to processing history and cannot be described using the classical Rayleigh scattering formalism. As a consequence, traditional loss reduction methods cannot be simply transferred to chalcogenide materials without an in-depth understanding of the kinetics of micro-structural evolution and loss mechanisms in chalcogenide films. The challenge of differentiating optical loss contributions in chalcogenide films is further compounded by the small interaction volume in thin films, which severely limits the sensitivity of most traditional optical characterization methods. In this project, new waveguide- and resonator-based spectroscopic characterization methods are developed to extract critical material information such as nanoscale phase composition, intrinsic absorption, and different scattering processes. The project advances our understanding of the nanoscale structural transformation mechanisms associated with material's optical characteristics as well as the structure-processing-property relationship in ChG materials. By combining kinetic modeling and experimental validation of novel surface-tension-assisted processing techniques, the project also aims to develop ultra-high-quality planar ChG structures with performance exceeding the current state-of-the-art.