Combining 2D Materials with 3D Nanostructures to Control Thermal Radiation

了解纳米尺度的热辐射对于先进的能源系统、纳米制造、局部热管理和高分辨率热传感/成像至关重要。微/纳米尺度的热辐射既涉及近距离物体之间的辐射传热，也涉及电磁波与微/纳米结构材料之间的相互作用，这种相互作用可以改变光谱辐射特性。石墨烯和其他二维（2D）材料的最新进展为当前的微电子、光电和光子器件以及能量收集系统提供了巨大的革命潜力。本研究项目的目的是研究二维材料与三维纳米结构杂交的潜在机制，以主动和被动控制热辐射输运和性质。上述结果对实际工程应用有直接的指导意义。参与本项目的研究生和本科生将获得小尺度热辐射的基本知识，以及在微/纳米制造、辐射测量仪器和数值模拟方面的研究经验。该项目的成功实施将对工程教育和人力资源开发产生重大影响，包括为代表性不足的群体提供机会。此外，本研究开发的计算代码将通过互联网提供，以促进未来的研究和应用。在金属光栅结构上制备杂化石墨烯，并用光谱仪测量其辐射特性，探讨石墨烯等离子体激元与光栅中磁性极化子耦合对光栅吸收或透射率的影响。门控石墨烯主动控制光谱辐射特性的潜力也将进行实验研究。基于严格耦合波分析的仿真工具将被开发并应用于模拟各向异性杂化二维/三维结构的辐射特性。例如，将研究与光栅结构耦合的六方氮化硼（hBN）薄膜，以揭示利用光栅在hBN中激发双曲波导模式。本文还将分析层状黑磷（BP）和其他二维/三维混合材料的远场辐射特性。通过将精确散射理论与各向异性RCWA相结合，本研究寻求理解耦合等离子体模式的近场热辐射，如混合石墨烯表面等离子体激元和hBN声子极化子（SPPPs），以及具有固有面内各向异性的结构，如少量BP层。此外，Kirchhoff？基于波动电动力学对各向异性介质的S定律进行了评价。将获得关于二维材料中的等离子体如何相互耦合以及在三维微/纳米结构中如何与共振模式耦合的基本理解，以及这些耦合现象如何影响近场和远场状态下的热辐射特性和辐射能量传输。该项目的成功将推动热辐射研究的前沿。

Understanding nanoscale thermal radiation is critically important for advanced energy systems, nanomanufacturing, local thermal management, and high-resolution thermal sensing/imaging. Micro/nanoscale thermal radiation concerns both radiative heat transfer between closely spaced objects and the interaction of electromagnetic waves with micro/nanostructured materials that could modify the spectral radiative properties. Recent advances in graphene and other two-dimensional (2D) materials offer enormous potential to revolutionize current microelectronic, optoelectronic, and photonic devices as well as energy harvesting systems. The objective of this research project is to investigate the underlying mechanisms of hybridization of 2D materials with 3D nanostructures for active and passive control of thermal radiative transport and properties. The results may directly benefit the practical engineering applications mentioned previously. Graduate and undergraduate students working on this project will gain fundamental knowledge of thermal radiation at small length scales and research experiences in micro/nanofabrication, radiometric instrumentation, and numerical simulation. The successful implementation of this project will have a great impact on engineering education and human resource development, including opportunities for underrepresented groups. In addition, the computational codes developed from this research will be made available via internet to promote future research and applications.Hybrid graphene on metal grating structure will be fabricated and their radiative properties measured with spectrometers to explore the effect of coupled graphene plasmons with magnetic polaritons in gratings on the absorptance or transmittance. The potential of gating graphene to actively control the spectral radiative properties will also be experimentally examined. Simulation tools based on the rigorous coupled-wave analysis will be developed and applied to model the radiative properties of anisotropic hybridized 2D/3D structures. For example, hexagonal boron nitride (hBN) films coupled with grating structures will be investigated to shed light on the excitation of the hyperbolic waveguide modes in hBN using gratings. The far-field radiative properties of layered black phosphorus (BP) and other hybrid 2D/3D materials will also be analyzed. By combining the exact scattering theory with the anisotropic RCWA, this research seeks understanding of near-field thermal radiation for coupled plasmonic modes, such as the hybrid graphene surface plasmon and hBN phonon polaritons (SPPPs), and for structures with inherent in-plane anisotropy such as few layers of BP. Moreover, the validity of Kirchhoff?s law for anisotropic media will be evaluated based on fluctuational electrodynamics. Fundamental understanding will be gained as to how plasmons in 2D materials can couple with each other and with resonance modes in 3D micro/nanostructures, as well as how these coupling phenomena may affect thermal radiative properties and radiative energy transport in both the near-field and far-field regimes. The success of this project will advance the frontier of thermal radiation research.