Research On Near-field Radiative Heat Transfer Between Microstuctured Metamaterials

Near-field thermal radiation,originating from the pioneering work of Polder and Van Hove,can break the traditional black-body limit and exceed it with several orders of magnitude.It has gained great attention in potential applications like cooling of electronics,active thermal management,and thermophotovoltaic system.Since heat-flux amplitude is critical in these applications,how to further enhance such near-field heat flux has attracted much attention in micro-and nanoscale research to date.As a kind of emerging artificial material,metamaterials can provide various possibilities in boosting near-field radiative heat transfer by means of nanopatterning.This dissertation aims at enhancing the near-field radiative heat transfer by employing metamaterials.A comprehensive study is performed to near-field radiative properities of alldielectric metamaterials.And we will give a rigorous numerical investigation of the role of Mie resonance in radiative thermal transport between the metamaterials.The framework of fluctuational electrodynamics that combines scattering matrix theory with the rigorous coupled wave analysis method is used to exactly compute the near-field radiative flux between Mie resonant dielectric cubic arrays.It shows that due to the excitation of Mie resonance,causing epsilon nd mu near-pole effects,the radiative heat flux could be spectrally enhanced in TM/TE modes.The discrepancy between the effective medium theory and the exact method is also elucidated in detail.In addition,the graphene metasurfaces are selected as an example to present the improving role of symmetric and asymmetric patterning in near-field radiative heat flux.Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled wave analysis is also employed to exactly calculate the heat flux.Especially,it is shown that the radiative heat flux between graphene metasurfaces with symmetric patterns performs a maximum 35-fold enhancement compared with the sheet counterpart.The enhanced heat flux is dominated by excitation and redshift of graphene-surface plasmon polaritons with high in-plane wavevector.The effects of substrate,vacuum-gap distance,and surface-geometry parameters between the two metasurfaces with symmetric pattern are also investigated.This dissertation opens an alternative route to enhance the metamaterial-based radiative heat transfer for efficient thermal-energy management at micro-and nanoscales.