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.
