We present a theoretical study of near-field radiative thermal rectification combining phase-transition and high-infrared-transmittance materials. The phase-transition material vanadium dioxide (VO2), with a metal–insulator transition near 341 K, is utilized under a reasonable temperature. Four types of high-infrared-transmittance materials, including potassium bromide, sodium chloride, polyethylene, andmagnesium fluoride, are introduced as thin film substrates under a VO2 grating on one side of the near-field rectifier. We explore the effects of various high-infrared-transmittance thin-film substrates and relevant geometric parameters on the thermal rectification of the device. The results show that thermal rectification can be greatly enhanced by using a one-dimensional VO2 grating backed with a high-infraredtransmittance thin-film substrate. With the introduction of a high-infrared-transmittance substrate, the rectification ratio is dramatically boosted due to the enhancement of the substrate transmittance. This work predicts a remarkable rectification ratio as high as 161—greater than the recently reported peak values for comparable near-field radiative thermal rectification. The results outlined herein will shed light on the rapidly expanding fields of nanoscale thermal harvesting, conversion, and management.

This work demonstrates the magnetic field-induced spectral properties of metamaterials incorporating both indium antimonide (InSb) and tungsten (W) in the terahertz (THz) frequency regime. Nanostructure materials, layer thicknesses and surface grating fill factors are modified, impacting light-matter interactions and consequently modifying thermal emission. We describe and validate a method for determining spectral properties of InSb under an applied direct current (DC) magnetic field, and employ this method to analyze how these properties can be tuned by modulating the field magnitude. Notably, an InSb-W metamaterial exhibiting unity narrowband emission is designed, suitable as an emitter for wavelengths around 55 µm (approximately 5.5 THz), which is magnetically tunable in bandwidth and peak wavelength.

Twisted two-dimensional bilayer anisotropy materials exhibit many exotic physical phenomena. Manipulating the “twist angle” between the two layers enables the hybridization phenomenon of polaritons, resulting in fine control of the dispersion engineering of the polaritons in these structures. Here, combined with the hybridization phenomenon of anisotropy polaritons, we study theoretically the near-field radiative heat transfer (NFRHT) between two twisted hyperbolic systems. These two twisted hyperbolic systems are mirror images of each other. Each twisted hyperbolic system is composed of two graphene gratings, where there is an angle φ between these two graphene gratings. By analyzing the photonic transmission coefficient as well as the plasmon dispersion relation of the twisted hyperbolic system, we prove the enhancement effect of the topological transitions of the surface state at a special angle [from open (hyperbolic) to closed (elliptical) contours] on radiative heat transfer. Meanwhile the role of the thickness of dielectric spacer and vacuum gap on the manipulating the topological transitions of the surface state and the NFRHT are also discussed. We predict the hysteresis effect of topological transitions at a larger vacuum gap, and demonstrate that as the thickness of the dielectric spacer increases, the transition from the enhancement effect of heat transfer caused by the twisted hyperbolic system to a suppression.